But in other phishing attempts the user actually gives out their password (unintentionally) to an unscrupulous actor. In this case there's a middle-man (the AI extension) doing that for you, sometimes without even confirming with you what you want.

I think this is more akin to say a theoretical browser not implementing HTTPS properly so people's credentials/sessions can be stolen with MiTM attacks or something. Clearly the bad behavior is in the toolchain and not the user here, and I'm not sure how much you can wave away claiming "We told you it's not fully safe." You can't sell tomatoes that have a 10% chance of giving you food poisoning, even if you declare that chance on the label, you know?