There are two C'Thuns that the game keeps track of. There's the actual card in your deck, and then there's the persistent aura attached to your character, represented as the C'Thun that pops up every time you play a C'Thun buff. The aura is what adds attack to C'Thun, and is what triggers the if your C'Thun has x attack cards.I wonder if that's true of a silenced C'thun? My guess is that "still triggers > 10 after Peacekeeper" is actually a bug, and that it should not trigger.
--Patrick