The characters here don't depart any further than those in, say, A Black Comedy or The Wastelands of Time, both of which are a lot further from canon than MoR,

The characters here don't depart any further than those in, say, A Black Comedy or The Wastelands of Time, both of which are a lot further from canon than MoR, widely acclaimed by some (including me), and not much hated by others that I've ever seen. "It violates canon!" is a rationalization of a strong ick reaction for other reasons. There may be parts of this that I don't fully understand, but I'm reasonably sure of that part.