There is even a chance with Manoah on the mound Wednesday, the Jays could lose still. So imagine the Jays lose, don't clinch home field and then don't have Manoah for the Wildcard matchup. Would be a huge letdown knowing he pitched in a game that didn't make a difference and that he can't be used fully for the Wildcard series.
If he pitches Wednesday, he would only have 3 days rest for a game on Sunday if it gets to a Game 3.