Come down off your pedestal, chief. You are taking the relative quality of the piece and applying your own subjective opinion to it. That's fine.
But just because you did not like the finale, it does not follow that from each and every other possible perspective it must also be terrible and only terrible. You are not the omniscient arbiter of quality, no matter how much you seem to believe you are.
Sorry, but you are the one on the pedestal here.
From his perspective - you know, the one that matters to him - the finale was shit. That's the end of it.
That others liked it or didn't think it was awful, doesn't change his perspective.
And, yes, he IS "the omniscient arbiter of quality" when it comes what he likes about his entertainment and what he doesn't like.