Well, Pog followed a 3k hard pull by Vingegaard on Tourmalet and didn't seem to be in major problem.
Then there is the fact that the drafting on the last climb was significant before the steep section, Pog wasn't close to the limit when Vingegaard attacked like he was the day before. Vingegaard's attack was also much weaker indicating that he was a bit laboured after the hard attack on Tourmalet and going deep the day before. Kwia even came back
. At that moment Vingegaard should have backed off, realizing there was a risk he could be attacked, and instead force Pog to pull. Remember that in that moment he was 53s up on Pog in GC, a good gap.
Sure, hindsight hindsight.