It's not a new challenge he wants anyway...it's an easier challenge. He looks at City and Liverpool, sees how much better than us they are and that we're probably not going to compete domestically for another year or two so wants to go back to Juve where the league for next season is basically already won, and he might get an extra cup and better chance of a champions league run too.
Bin him off. Can't stand all the publicity and whatever around him. Everything is about Pogba. On his day, yes, he's excellent. But how many days has he had in the last 3 years? Count them on one hand I reckon. From the reported €150 million, you could build most of the midfield that actually works for the style of football Ole is aiming for.