I don't know who Casey is, but it sounds as though he's not been well handled or trained.
As for rubbing his ears on poles, well I've never yet met a horse who doesn't rub some part of their body on poles/fencing etc. If he does it more than usual, maybe he has an ear problem or ticks in his ears. Has anyone bothered to find out?
I've known a few draft Mules and ridden one quite a bit years ago. She was wonderful to ride.
A well trained Mule, is no different from a well trained horse. Untrained either, can spell disaster.