Yeah she does, that's what I mean. BoJo is a guest, he gets asked a question by Host nation press (US), does the decidely polite British thing of being a good guest and allows the question (why wouldn't you?) then the whole room is evacuated.
BoJo is a man who was under fire every day during his role of London Mayor. He had to answer to some commitees and panels, one of which he did with zero notes in front of him and still made them look like fools. He knew the material better than them. The guy can answer off the cuff. Hell PMQ's on a wednesday is a few planned talking points and then "hit me with what you got"
Kicking out the press to stop Biden making a fool of himself, when everyone already knows he's a fool, is pretty stupid. Now everyone knows he's a fool and can only answer set, remembered and rehearsed questions. Not a good look in front of a foreign leader.
Luckily this was the UK, a close ally. Imagine if this was the taliban, or russia? You'd have Migs over Washington by tea time.