 Probably because his handlers have told him to swing his arms when he walks. It's something we all do naturally, but it goes away in Parkinson's disease. Gait instability. Soft voice. This part. On and off periods. Times when the medication seems to be working well and when it isn't. And at some of those times where it isn't, it can get that person more animated or they're suffering from something else. Mm-hmm.