He was hurt most likely at some points throughout that season, but I'm not talking about Pogba specifically but just any top professional footballers who compete at the highest level can have a huge amount of games to play in a year. If you think they're giving 110% on those meaningless cup games with important league games coming up as they're coming back from injury, you're out of your mind. He's getting back in shape in a worthless competition, he's not playing a CL final FFS.
It's naive because it's not rooted in the reality of professional sports and it happens all the time, players aren't machines that perform at peak intensity even in meaningless cup games. They're going to have to pace themselves and that inevitably means picking and choosing which games you will go full clip at. These kinds of third rate league cup games shouldn't even be played by players like Pogba, they're a waste of time but in his case, this was just a warm up to get back into shape for the games that actually matter. I don't think Ole himself would want Pogba to go at 100% on his first game back against semi-professionals, it's just nonsense if you're looking at the big picture.