Not sure if I missed something but not sure what justification he gave that Open Weights would improve safety.

The counter argument from Anthropic is easy. If we open weights we can't detact it after being published / the guard rails that run on top of the models would be lost. Also abliteration would be much easier to do when a model's been publically release.

I'm not a fan of Anthropic but the argument in the article seems stupid.