OK, I watched the end of the game, and the announcers (former MV coaches Bergman and Babcock) admitted they could not tell what had caused the penalty, other than the flag was thrown in the MV backfield after the TD and it was for unsportsmanlike conduct. My guess is an MV player taunted or made contact with an SRV player after the TD. The announcers further stated a similar call was made on the first MV TD earlier in regulation, so someone didn't learn from their first mistake, whether it was the same player or the coaching staff not correcting that behavior with the whole team.
Without knowing just what the call was, it is hard to say it was a bad call, much less the refs deciding the game. Still, even if it was a bad call, the TD still counted, and the 15 yard penalty was assessed on the extra point. So instead of a 20 yarder it was a 35 yarder. MV had every chance to make that kick to tie the game and force triple OT, which they evidently must have done after the penalty in regulation as they got the 7 points. But the kick was blocked. It was hard to tell if the distance affected the kick, the SRV played just made a great play, or it was just kicked too low. It was unfortunate for MV and very poor timing, but it was the second time it happened and they made the kick the first time around.
This is a great rivalry (I've been to a few of these and they are intense) and these 2 teams may very well have a rematch in 2 weeks, as there is a good chance they'll be the #4 and #5 seeds in the NCS D1 playoffs. I'm sure coach Russi & staff will have corrected whatever unsportsmanlike behavior occurred by then and it'll be another EBAL Mountain barn burner.