It is an interesting question, but what if we imagine MacKinnon scores like 180 points and has a Conn Smythe performance, while McDavid gets "just" 120 with sort of usual playoff performance, wouldn't that be enough to say "Sorry, Connor"? I mean, I think even considering like the best player reputation as a bonus factor there should be some performance level when the other guy is good enough to steal the crown.
It would be in my view an outlier unless he follows up next year with a much better point total than McDavid.