LePage would have still won in a two-way race IMO. Silly to blame Cutler.
If you only look at the margin on election day, yes. But you also have to take into account that throughout the entire campaign Michaud was getting hammered by both LePage and Cutler. Cutler consistently talked about how they were both the same, therefore cementing in his supporters' minds for there to be no meaningful preference for Michaud like there was at the start of the race. Had Cutler never entered at all, LePage wouldn't have been Blanched/Corbetted, but he probably still would've lost.