If it was ruled a goal, I believe it would have stayed a goal,
That's not really how challenge works i think. That's how the video reviews from Toronto work. The challenge decision is made by the referees on the ice (one of them is the same guy who made the call on the ice) based on what they see in the replay. What they previously called or saw don't really matter if they think a bad decision was made based on the replay (unlike video reviews where the replay needs to be 100% conclusive).
What probably happened is the refs thought PB did not make a worthwhile effort to avoid the contact with Price. Even when a player is pushed the rule says that he still need to make an effort to avoid any contact with the goalie. A similar decision was made against us last year. Gallagher was crosschecked hard in front of the net and felt on the goalie. A second later a goal was scored. The goal was disallowed cause Gallagher even if pushed did not try to mitigate the contact with the goalie.
If you look at the replay PB while pushed is not pushed that hard to be honest (let's say PB makes it easy for Emelin to win the battle). He is pushed outside of the crease and he ends up at the end of the play right in the middle of said crease. PB lost his balance after being pushed by Emelin but that's not really Emelin or Price problem. That's the NHL if you can't fight for your space in front of the net then you don't belong there.
I would have personally allowed the goal but i've seen far, far, far more controversial decisions. The Gallagher's disallowed goal last year was far more controversial as he was crosschecked hard into the goalie.