The incident wasn't at the net, it was more at the blue-line by the one bench. Prosvetov stopped at center ice while Incze wasn't more than 30 feet away. I'm going by what I saw on the TV; looked very much like Prosvetov was 50/50 on joining in. Looking back at previous goalie scraps (or near scraps), they just went for it - Josh Unice (only to be stopped by official), Engelage/Pasquale, and Nichols/Guigovaz.
If you see a goalie go after your teammate, you either jump in or you don't. Like I said above, every goalie fight (or near fight) I've seen had zero hesistation. Jump into the situation and the center line isn't even looked at.
I'm all for them going if need be. I can see why they wouldn't, of course, but I fully expected Prosvetov to ignore everything and b-line for Incze. It didn't happen.