Trudeau pauses 21 seconds on question about Trump's actions [video]
cbc.ca
cbc.ca
Personally, if talking to another person, I would look down or away if formulating (or trying to give the impression that I'm formulating) an answer. Rather than look at the person uncomfortably (on the part of the other person) for 21 seconds -- maybe that's because in person, if you look at someone and say nothing for a long period it invites them to fill the gap and say something instead.
Perhaps it's different or he thinks about it differently because he's looking at a camera? Or it's a one-way press conference?
It does just look odd though. Not to say he shouldn't take time to answer important questions -- and in fact more public figures should do this. But I would just naturally think he would look down or away from the camera while doing it, to indicate that some response is coming during the silence.
He is always extremely careful with his words, and doesn't really hide it when he is calculating his responses. The benefit of course is that he very seldom speaks out of character or says things he didn't quite mean. Sometimes it backfires if he translates from French to English first, causing him to come up with great phrases like "speaking moistly" when describing ways Covid-19 can spread.
People used to make fun of his continuous "uh," but when you realize he grew up in and around Quebec, that speech pattern makes sense as well. Quebec French has a really specific sort of "errr" (my spelling does it no justice) where English speakers would say "um" or "ah". He uses a sort of anglicized version of that sound because it is the norm where he grew up.
Literally a lot of things in his mannerisms that people joke about or point out as odd in some way come from Quebec. And others are because he does the full translation in his head before speaking.
The 21 second pause is, for him, only unusual because of the duration. It would be interesting to capture the thought process he was going through before breaking trance to speak. It clearly was an answer he had difficulties putting together in both languages while retaining his signature tact.