He might have been trying to brake, but it was too late, and he was going to crash into Rinne regardless of whether he got hit from behind or not. He might not have crashed into him as hard, but contact still would have made in the crease, and such contact is an easy goalie interference call.
Having said that, I am pretty sure that that would have been declared a goal for certain teams in this league...Penguins, Blackhawks.