I don't know if it is relevant in any specific case that is being discussed here, but if the exploit route is via gaining access to the accounts of previously trusted submitters (or otherwise being able to impersonate them) it could be a case of teams with a pile of PRs to review (many of which are the sloppy unverified LLM output that is causing a problem for some popular projects) lets through an update from a trusted source that has been compromised.

It could correctly be argued that this is a problem caused by laziness and corner cutting, but it is still understandable because projects that are essentially run by a volunteer workforce have limited time resources available.