As for his 'blundering' in a live Q&A talk, that's not indicative at all, I have posted my reasoning in a sibling comment.
There are two answers to this question. One is obvious and is the subject of the article we're all responding to: Cheating. Some people think he's cheating.
The other is that nobody actually thinks Hans is terrible. Even if he cheated he's still at least a 2500-level player and perfectly capable of taking the odd game off of super GMs. Being very good and cheating aren't mutually exclusive possibilities.
> that's not indicative at all
The word you want is conclusive. The interviews are certainly indicative, but they're very far from conclusive.
No. The word I want is indicative, as in "Serving to indicate; Pointing out; bringing to notice; giving intimation or knowledge of something not visible or obvious".
Giving "imprecise" analysis at the Q&A session does not mean anything at all, and of course it can't be used as an evidence of any kind that a cheating took place.
Specifically on this, I agree with you. Who knows if he's just nervous at giving interviews.
The interviewer (Alejandro Ramirez, also a GM) asks Hans what happens if black takes the knight on c4, which didn't happen in the game but is the engine's best move. Hans says Bh6, starts down one line with g6, Bg5 (good moves) but backtracks the latter and blunders with f4, and says "At this point my pieces are literally perfect, his pieces are terrible" (Hans is -2). The position in the video is two moves later. By then white is completely lost, but Hans says black has no chance.