Large holders of Tether would be pretty dumb to short it, as they'd be shooting themselves in the foot. If Almeda indeed knows something the rest of the market doesn't, they would (assuming rational action) quietly be exiting their position.
They could do both, cut their losses by selling and selling high, buying low other people's Tether, depends on how much of their own holdings they can liquidate.
depends on the payout if your short is better positioned than your holdings...you short. Like Deutsche did 2008.