I'm not sure if one can blame the goaltender for actually playing the puck behind the net. Often, the puck rings around the back boards and the goaltender has to place his stick blade right next to the boards to stop the puck. Should Smith be at fault for having his body too close to the boards? When goaltenders stop dump-ins by the opposing team, they are still right next to the boards behind their own net. He had every reason to want to play the puck, and was in the same position most would be to play it.
Here's Smith playing the puck a few years ago as many would do. Notice the space between is between the goaltender and the net, not the goaltender and the boards:
0:28:
The Rangers player, Dubinsky, in this case, stops. He could have curled along with the opposing player but instead respects Smith's positioning and stops. The Lightning player skates between the large space between Smith and the net. This is with both of them jostling for position as well. Edler misplayed it despite having an incredible amount of time to react and actually turning in towards Smith.
Cory Schneider here plays the puck at the boards. The space is between the goaltender and the net:
If the goaltender has left the boards already and provided a space, it is because he is returning to the crease. When the goaltender is playing the puck at the back boards, which Smith clearly was, the space is between the goaltender and the net.
Here is one such play you may be referring to:
2:15 -- Cory playing the puck. He has already played the puck before the Hawks player arrives, thus giving him space at the boards as Cory returns to the crease. Had the Hawks player been closer when Schneider was playing the puck, his lane would have between between the goaltender and the net. This is a case of nobody being around when Cory plays the puck, which is often the case in dump-in scenarios. The space between him and the boards opens up because Stalberg is late to the puck:
When the goaltender is in the midst of playing the puck, he is naturally at the back boards because that is where the puck is going. Edler could either have stopped as Dubinsky did or go between the goaltender and the net as Lundin and Morrison did. He was watching Smith the entire time and decided to skate right into him.