They've been "negotiating" with Ukraine's invader behind Ukraine's back. Concocting mineral right "deals" that they believe Ukraine _must_ accept; without their involvement and without security guarantees. Voting "against" them in the UN. Making false statements about who invaded who. Etc.
And he's gonna not, rather politely, push back and ask questions instead of getting steamrolled? They started this off with Brian Glenn grilling him over his lack of suite and accusing him of disrespect while they snickered and sneered. Let's not forgot that those "jokes", and this entire presser, are in the context of an ongoing war with nearly 1,000,000 dead and wounded now.
If anything I think Zelensky smoked them out for all of the US public and Europe to see. Why would he avoid that?!