Every single one of those sentences is highly dubious. Cyber-defenders would be pretty jazzed about having easier access to Mythos-class models. Cyber-defense is easier with better tools.
Handing every skiddie and nation state and APT and hacker group access to Mythos does not help cyber defenders
Even if you don't think Mythos is a big deal: At a certain point models become smart enough as to be dangerous, and you don't give everyone a superweapon. Open source has an end of the line sooner or later.
Luckily, Anthropic has no such monopoly, so the point is sorta moot