That's a really common gesture when describing someone who's trying to deny they did anything wrong, At least in the NE where I grew up. Trump was talking about journalists in general who lie, then say they didn't when pressed about it. Trump's gestures fit the optic he was trying to paint, as they always do. He had done that same gesture often when addressing liars in speeches.
Handicap BS is a stretch that only true believers would grasp on to, IMO.