I had a game. I played taxman and my opponent didn't discard, nor reveal his hand, nor reveal a Moat.
I couldn't get the number of the game, but it was just right now. My name in the game is MarcMF and my opponent was UNKNOWN_379726
Note the bolde part on the text of Taxman:
Taxman
You may trash a Treasure from your hand. Each other player with 5 or more cards in hand discards a copy of it (or reveals they can't). Gain a Treasure onto your deck costing up to $3 more than it.
As you had attacked your opponent with Torturer before during that turn, they had only 3 cards in hand when you played Taxman, so they were unaffected.