Although, they also said, "Because the patches appear to be written by humans".

"Mythos writes code like a human" incoming

The patches could have been written by humans, it doesn't matter that much. Or written by a clanker and polished by engineers. The difficult part is usually not in writing the patches that fix such vulnerabilities, but in finding the vulnerabilities. And these days it's even harder to exploit them, since you need to bypass modern hardening features.