I think it will come with time as he adjusts to the pro game, when your 6'7 I imagine it would be pretty tough to pick your spots especially when everyone's head is around the same height as your shoulder or less, he does play physical its not as if he avoids it. Maybe he just feels it would be easier to use his long reach and good positioning instead of trying to hit a player and get a questionable penalty that may hurt his team.
I was at the game last night. It was the first time I'd seen Oleksiak in person, and I was actually surprised at how overpowering he was at times. He wasn't throwing giant hits, but there were at least three times when from a stand still he reached out and shoved someone and they went flying onto their ass. I guess it's just a matter of getting him to do that more often.
Also, Cody Eakin's hair is freakishly red. That is all.