Clearly this situation is a lot more substantial than the giftcards he gave away. If you think people saying thank you is obnoxious to the point that it bothers you then you should evaluate your priorities..
There's nothing wrong with saying Thank You but making a public announcement out of it seems wrong.
Like a Calcutta begger who rolls around the floor, kissing your feet, because you gave him $5
I'd much rather have a dignified (and private) hand shake/thank you.
Unless Scooby donates the cash because he craves the attention....?
But I doubt he does
He probably finds it a bit embarrassing.