Anthropic CEO Dario Responds to Safety Concerns in a Long Post, Reveals High-End Model Was Held Back for Four Months

Anthropic CEO Fires Back with a Long Post! Reveals He Shelved Mythos for 4 Months, Cutting Off Revenue for AI Safety Xinzhiyuan October 22, 2026 06:34:13 From Beijing Updated October 22, 2026 07:17:37

In Silicon Valley in the early hours, the air is thick with the smell of gunpowder.

Just moments ago, Anthropic's head Dario uncharacteristically lost his cool on X.

He personally dropped a hard-hitting post of nearly a thousand words, directly countering the most cutting accusation the outside world has made against Anthropic—

In response, Dario for the first time revealed—

A fully trained Mythos-class advanced model was kept under wraps for about four months before the public was allowed to touch it.

He laid out, item by item, "the money his company had actively lost over the past year for the sake of safety."

In an industry where a model can rewrite the rankings every few weeks, four months is enough time for round after round of new models to take the stage.

Choosing to wait very likely cost Anthropic a considerable portion of what had originally been a months-long lead.

"Anthropic Just Wants to Win the Superintelligence Race"

This time, the one who forced Dario to show his true colors was Nathan Calvin, a well-known investigator in the AI safety field.

A few hours earlier, Calvin's thousand-word polemic instantly set the entire AI world ablaze.

He pulled out a long list, dissecting with surgical precision Anthropic's "nine sins" over the past year.

Splashing out a $500 billion compute mega-deal, secretly forming an in-house chip team, letting Claude take over 26% of internal R&D tasks for "self-iteration," quietly revising safety commitments...

Calvin's subtext was scathing: Stop pretending—you just want to build superintelligence before everyone else!

Calvin and several policy researchers were furious after reading the draft, believing that the bill Anthropic was pushing behind the scenes looked like a call for regulation but actually hid ulterior motives—

Anthropic's federal affairs head Anthony Cimino originally wanted to post over the weekend to put out the fire, but instead completely ignited Calvin's powder keg.

Calvin fired off a series of soul-searching questions: What kind of company is Anthropic, really?

If you go by what executives say in their open letters, it is a "safety institution" always ready to hit the brakes for humanity.

Not long ago, Dario also publicly warned that AI clusters could take over the entire internet within the next 6 to 12 months, and called on the whole industry to slow down.

Calvin stabbed coldly: If the nine things above had been done by OpenAI, Anthropic's employees would probably have jumped out long ago to curse them out and treat it as ironclad proof that their rival is "blinded by greed and indifferent to humanity's fate."

Dario Lays Out the Ledger Late at Night

How Much Revenue Have We Cut Off for Safety?

Facing accusations that threatened to overturn the company's moral foundation, Dario did not hide.

At the start of his response, Dario first showed some high emotional intelligence, thanking Calvin for his oversight, but once the pleasantries were over he drew his blade.

Right after that, he laid out in one breath nine "self-harming moves" that would give countless Silicon Valley investors chest pains just looking at them.

A God-Tier Model in Hand, Deliberately Shelved for 4 Months

This is the most newsworthy bombshell in the entire post.

Dario publicly admitted for the first time: as early as February this year, Anthropic had already trained a "Mythos-class" high-end model.

But Anthropic held back.

At the time, the cybersecurity defense mechanisms for models of that class had not been fully polished, so they chose to open it only to a very small number of partners, specifically to strengthen cyber defense testing.

It was not until June this year, when the safety guardrails were in place, that this model was officially opened to the public.

A full four-month lead window, in a race where every second counts, was cut off by their own hands.

Dario said outright that it was precisely because of this four-month buffer that many enterprises were able to shore up their security infrastructure before AI models with powerful cyberattack capabilities became widespread.

On June 9 this year, Fable 5, which Anthropic launched to ordinary users, belongs to this tier and comes with strict protections.

Mythos 5, released at the same time, first offered partially lifted restrictions to a small number of cyber defense and infrastructure partners.

Therefore, during the "shelved" period there was still restricted use; and when it opened in June, there were also different access boundaries.

Of course, he did not provide a quantifiable bill for exactly how much revenue was lost by waiting, or how much risk was avoided.

"Zero Tolerance" for Biological Risks

The cost in the biological domain is especially painful for Dario. He himself has a background in biology.

He said the company saw worrying results in biological capability tests and had intercepted potential attempts at biological weapons misuse, so it adopts strict protections for high-risk uses.

The problem is that filters have a hard time accurately reading everyone's intent.

Letting a dangerous request slip through is a false negative; blocking normal research is a false positive. To minimize the former, Anthropic accepted a large number of the latter.

Legitimate researchers were frustrated, and competitors would even use "fewer restrictions" as a selling point.

Users bear this cost too.

Anthropic's previous official explanation confirmed that when Fable 5 triggers the biological safety filter, it hands the request to a less capable model.

The August update reduced biology-related fallbacks by about 85% in company testing, but still retains restrictions on dual-use research.

Another item on the ledger is regulation.

Dario said Anthropic pushed for legislation such as California SB 53 and even supported a version stricter than the one ultimately passed. In June this year, he also publicly argued that the government should have the power to block model releases.

That amounts to supporting external forces holding the switch to its own products.

Finally, the 5% equity stake. Just a few days ago, Anthropic announced that it plans to put 5% of the company's shares into a public interest fund, pending shareholder approval. Once the company's valuation exceeds a specified benchmark, the board may also add 2% at its discretion for every 50% increase.

Why does a company that insists on safety still desperately buy compute and accelerate R&D?

The core logic Dario gives is called "race to the top," competing toward higher standards.

Calvin's worry is also direct: if every round of competition must be won, how much more can safety make the company yield?