All the evidence says that Ryu has been better with an extra day of rest. There are plenty of Montoyo decisions worthy of criticism or derision. The one he made where the supporting evidence actually validates it isn't one of them. Because sometimes you can make the right decision and it still doesn't work out.
It's also being lost that the Rays are a significant favorite for a reason. This is not the Jays as a marginal underdog to Tampa Bay and blowing it against a team they've beaten up on all year. Tampa is the #1 seed. Toronto is the #8. They had a losing record against the Rays in their limited action this season.
Maybe getting obliterated 7-1 in the 3rd inning of game 2 wasn't the plan, but losing the series to the Rays is in no way an unexpected outcome. The fact that the Rays are winning the game and probably the series probably has as much to do with them being the better team as it does with Montoyo being a questionable MLB manager