I watched and he did what I've done to no-threat guys that sat on all day. Let them go and team up with riders that are threatened and encourage them to work. You can take energy out of multiple opponents at the same time and not burn your matches. Do you honestly believe that if the Tour was in the balance that Tadej wouldn't have stayed with Vingegaard? He gave him a gap of, what...19 seconds at 1.5 km from the top? He checked how close the two were following before backing off. Carapaz and Uran, who was in position to get 2nd on GC by leaving O'Conner behind were very willing to drive pace all the way to the line; which they did. And caught Vingegaard who got nothing but, in your mind; a false sense that he might be stronger than Pogacar.
Oh...showing weakness is how you beat other teams on occasion, particularly when you want their young debutante' to overcommit. Unless you've been a winning GC guy and that was your biggest fear, then OK.
The consequence of that sense will be very real - Pogacar will now face more attacks than he would have - had he not show this supposed weakness. While 2 days ago it was unimaginable that he cracks, now Ineos and TJV will try something in the Pyrnees. Surely that's not in Pogacar's best interest.
And as some people already mentioned here, it would make sense to stay with Carapaz and Uran from the beginning and let them do the chasing. That would be a valid and good tactical decision and noone would say he did that because he couldn't follow. But that was not his intent because he reacted to Vingegaard's attack and he would have stayed with him if he had the legs.
And then finally, there's that acceleration at the end of the stage. Does one who is concerend with burning matches do that? No he doesn't. There's nothing to gain there in the end, sprinting is pointless. Yet he sprinted. Why? Because his ego was hurt and he had to show he's still the alpha.
That's the way of Pogacar. He doesn't let people go - he follows them if he can and humuliates them if possible. In his optimal scenario yesterday, he would first follow Vingegaard and then a couple of hundred meters later, he would attack himslef, dropping Vingegaard and catch the Trek boys before the summit.