

I think it’s because he hoped there were actual guarantees, considering Trump is definitely interested in Ukraine’s mineral industry. But as the meeting went on it became increasingly clear that keeping Putin his BFF was even more important and he just wanted to have his cake and eat it too.
I still think the ultimate outcome wouldn’t have changed but yeah, rewatching it he does seem a bit more provocative than in the rest of the interview. Maybe it did tick him off a bit too much and he decided to go for it in the heat of the moment.