I already said they could have done more. They could have forced MFA.

All the other bullet points were already addressed: they used a botnet that, combined with the “last login location” allowed them to use endpoints from the same country (and possibly even city) that matched that location over the course of several months. So, to put it simply - no, no, no, maybe but no way to tell, maybe but no way to tell.

A full investigation makes sense but the OP is about 23andMe’s statement that the crux is users reusing passwords and not enabling MFA and they’re right about that. They could have done more but, even then, there’s no guarantee that someone with the right username/password combo could be detected.