a1 shoots a jumper and misses with a high bounce off the rim. b1 and b2 jump for the rebound and collide. b1 gets the ball and b2 falls out of bounds, b1 with the ball extends a hand to help b2 up while b2 is out of bounds and b2 takes his hand.

should this be a violation?

No violation, unless B2 makes contact with the ball while standing out of bounds.

NF 7-1-1
A player is out of bounds when he/she touches the floor, or any object other than a player, on or outside a boundary.