> Surprisingly, I think no attacker has ever forged a OpenPGP signature in a real-world security incident, likely because there's a lack of overlap between crypto nerds and crackers.

I suspect in the real world almost nobody validates PGP keys of software downloads manually. They might do it automatically (for example via a Linux package manager), which a fake key wouldn't fool. Thus, faking the key isn't necessary because 99% of users that could be fooled won't bother checking.