Was the main contact the shoulder? I’ve seen the replay and still can’t be sure.
Looked like it to me. Often when you deliver a hit you ride up, and it looked like because of the angle of the way Reese was coming at Wilson and bracing for the counter hit/trying to avoid as much damage as possible, Wilson hit his shoulder on his shoulder and rode up into his head as he was bracing. Wilson's feet does come up AFTER he delivers the hit however so it looks to me that him rising is a result of the impact. Like if you look in slow motion his one foot does not come into the air until after he's deliver initial shoulder to shoulder contact, and then the momentum causes him to rise and hit the head.
I don't know about discipline on this one. No penalty on the ice is a big deal here imo.