Alternatively, if Biden walking around Kyiv with air-raid sirens going off* is good PR, showing solidarity with Ukraine and personal courage, then Kyiv or the President’s train coming under fire while Biden was there would’ve been even better PR (albeit not something I would hope for). Ducking – more realistically, going into a bomb shelter – isn’t a lack of courage, even if certain elements of the media would spin it otherwise.
It’s not the same thing, of course, but Buckingham Palace being bombed in the London Blitz didn’t cause the British public to wonder what the royal family was doing in harm’s way, it caused them to respect them more.
*I understand the sirens were a call to a moment of silence, not an actual air-raid warning.