Imagine sitting in airline seats, side by side with a 6-3 300# seat mate, and they will want the armrest up because it digs in to him.
No choice to hang into the aisle, there is no aisle, it's the side of the fuselage.
Which means he's going to take part of your seat. Many side by side seating has controls between the seats. It's just not going to work.
He will not fit in a 2-33, he will bust out the plastic side pieces and jam the rear seat rudder pedals.

I've had large potential students visit and the discussion turns to weight. I don't have a glider you will fit in. These are max rated at 242#.
But we are not flying so go ahead in get in. With a little guidance they finally fit into the seat of the Grob 103 and realize they have no room to move and cannot get full deflection of the control stick.

BillT