First, I like Al Montoya. I've always liked him, in fact.
Now, this is a horrible coaching call. You don't take a red hot goaltender out of the line-up on a "must win" game in a labor shortened season. This is just ridiculous. It's decisions like this that will keep us out of the playoffs. Again, I have absolutely nothing against Montoya, but this is not the time nor place to slot him in the starting lineup.
Am personally never a fan of starting recently moved goalies against their former teams. I get the theory that the recently moved player is supposedly motivated to play well against his former team. The other side of that coin however is that if there is anyone that a John Tavares-type of player knows how to easily beat... it is the goalie that he faced in practice on a daily basis. That sort of familiarity breeds knowledge of any tendencies and weaknesses.