The squeeze will be on them...who will in turn give up the goods on Giuliani. And we all know Rudy is well under water with legal bills. Dominion machines will own his soul soon. Once Rudy figures out he has been thrown under the bus by the Liar in Chief...you can expect him to sing like a bird.
So...the committee does not have to call trump. He was the man behind the sedition attempts. It will become obvious to everyone.