It is likely that repetetively locking and stressing an elbow in full flexion is bad for the joint and surrounding soft tissues.
Bear with me here.
If you consider campussing, you could essentially do a one armer, lock in full flexion, then reash statically to your next rung. this involves high stress on the elbow in full flexion.
Alternatively, you could pull hard and initiate upwards movement, then use this momentum to continue height gain as you reach through to your next rung. Strain is mostly applied to an extended elbow to initially flexion.
Of these two methods, I would suggest the latter is less likely to give elbow problems. I suspect this may be what Dave is getting at, but I ain't going to start second guessing him.