I guess I was hoping to find a direct reference that a new 'Official FAQ' would clarify the topdecking rule, something like
"... his ability does not function if cards are put into your discard pile without being discarded, such as when you buy a card, when you gain a card directly (such as with Border Village), or when your deck is put into your discard pile (such as with Scavenger from Dominion: Dark Ages), or when a card is placed on top of your deck (such as with Bureaucrat from Dominion: Base Set)..."
Although topdecking is not mentioned by name, the other examples given, along with the second FAQ entry I quoted, make it completely clear that topdecking wouldn't count. The real question is, why would it? If you think topdecking would count, why wouldn't playing a card count? Or drawing a card? Or passing one to an opponent with Masquerade? There are a bunch of different things you might do with a card... play it, trash it, discard it, topdeck it, pass it, return it to the supply, gain it... topdecking and discarding are no more similar to each other than any of the other options.