Conventionally a tenor trombone is held in the left hand, with the bell crook over the left shoulder, and the slide is moved with the right hand.
Is there any reason a left-handed player shouldn't have the bell crook over the right shoulder and move the slide with the left hand?
I realise some trombones have a trigger, which expects the player to be right handed and operate the trigger paddles with the left thumb. But if the trombone itself didn't have any triggers, is there anything more than convention that dictates it be played right-handed?