Why not? During the shift on an earlier shot, Quick exploded to his left laterally in order to make a save on a Russian shot, and his skate hit the post and jarred it out of the moorings. You can see the that the net is off as the puck beats Quick here:
As you can see inside the green circle, the piece of the post that goes into the hole in the ice that holds the net in place is horizontal long the ice, meaning the net is off.
The net being off didn't prevent Quick from stopping the puck, and in fact it actually gave the shooter a worse angle, so the goal itself wasn't impacted by the net being off, but the rules are the rules, and here's what they are in the IIHF:
471 - DISALLOWING A GOAL
a) No goal shall be allowed:
1. If an attacking player deliberately kicks, throws or bats with the hands or otherwise
directs the puck by any means other than his stick into the goal net even if the puck
has been further deflected by any player, goalkeeper or official,
2. If an attacking player contacted the puck with the stick above the cross bar,
3. If the puck has been directly deflected into the goal net off an official,
4. If an attacking player stands or holds his stick in the goal crease when the puck
enters the goal net, unless he has been physically interfered with, by the action
of any defending player so as to cause him to be in the goal crease when the puck
enters the goal net, unless if in the opinion of the Referee, he had sufficient time
to get out of the crease or unless Rule 470 applies.
5. If the goal net has been displaced from its normal position, or the frame of the goal net is not completely flat on the ice.
Point 5 is the pertinent part. If the integrity of the net is altered at all, it's no goal. Good luck for Team USA.