A bottle jack pushing between L and r leg might work.. Depending on how/where R leg is. Adding wood/shims between wall and r leg to make a solid pushing surface..Took the top frame out and opened the corner to somewhat work around the twisted leg.
Can't do it with a clamp cause I'd like a good tight bar clamp.
Bought multiple brackets and more lumber to support the upper half lot better. Will post a mock up or something when I can.
Also a good size lag screw and a socket wrench could pull it together..
I've pulled twists w just using drywall screws but it all depends n how tight the twist is..