Isn't Thanksgiving more deserving of a naysayer? I mean, really, we eat dinner every day. Is it that for Thanksgiving--as opposed to Christmas--you are only asked to give thanks, not presents? To give thanks and eat dinner. But you must give thanks and eat dinner in a way that outdoes the thanks-giving and dinner-eating of other days. I do think there should be a Scrooge/Grinch analog. The Thankswithholder. The Ingrate.
UPDATE: Midwestern Mugwump suggests "Thanksgriper."
ALSO: More here.