I think its more Sutter giving Markstrom a chance to redeem himself than being stubborn. He probably wants to see how he responds and if he can build his confidence back up. I think Vladar will start to see more time this season if/when Markstrom doesn't look right.
Elimination game is not the time to give a bad goalie chance for redemption. Markstrom was bad that series. He had plenty of chances to prove himself and clearly looked like crap.
If Sutter is gonna risk the whole season over 1 individual's feelings and 2nd chance then that's a stupid move. It's a team game. He didn't hold Markstrom accountable like every player should be held. Dumb move by Sutter, whatever his reasoning was.