The US government basically told them they can't sell "Fable" and so they aren't. That's probably 90% of the story.

Once the government stepped in, their 5th generation was effectively killed. They either had to lock it up (Mythos), neuter it (Fable), or leave people with the perception they were overpaying for a weaker model (Opus 5).

Hopefully Anthropic has learned to anticipate this risk and has a plan for rollout of their next model that plans for capricious ad-hoc regulation.

The government seems like it's in a rough spot. If they let Mythos out, they seem worried people could use it to mass-hack the internet. China seems to not care so much about this and they're right behind. I don't really know what the answer is.

What did they think was going to happen when they were actively doomsday fearmongering around the release of their own model? I assume somehow they thought this would lead to a moat with them being left safely inside the castle, but this response, and Reagan's 9 Words, were always infinitely more likely. It was a demonstration of a child-like level understanding of how regulatory capture works.