There is an assumption being made here that isn't being made explicit: the only way that malicious behavior can be avoided is by paying a programmer. Is that a valid assumption? Or the less strong: a plugin is less secure if developed by a coding agent when compared to any possible programmer. Is that a valid assumption? Aren't all of the well-known issues in WordPress plugins the fault of programmers?
What I feel in these comments isn't a genuine attempt to engage but rather Fear, Uncertainty and Doubt (FUD) writ large.
Also, for what it is worth, the most recent project he developed was using React, Tailwind and Postgres (which he called "Post ... something?"). It was very work-flowy (user uploads a doc, it goes into a queue for manual review, once approved it is converted and uploaded to Google Docs, an email is sent, etc). I asked him if he had investigated any workflow builders and he said no, he just vibe coded it. It's also worth noting that he is paying for QA, I think that existed already in house for his other projects. Well, actually what he said was "it is currently in testing", so I can't confirm if it is professional QA.