Comment by zarzavat

There's a much simpler explanation: Amazon's business is selling cloud services. Amazon is constantly under threat of attack and anything that disturbs the balance between attackers and defenders is bad for Amazon. Amazon also needs to keep their AWS customers safe.

This is Amazon prioritizing their 100% stake in AWS over their 20% stake in Anthropic. It's also possible that Amazon knows things that are not public.

The fact that Amazon is willing to report this despite owning shares in Anthropic and being close to a liquidation event points to whatever they found being actually serious.