Nice comments with which I agree.
Does it make sense to forcefully drive this internal rotation of the support leg? I prefer the support leg weight to be more on the ball of the foot and lightly in contact with the ground so that it can move to follow the swing leg. I imagine this reduces the torque on the lumbar spine?
The exercise is swinging a leg back and forth. If we fear this too much then why train! Everything in moderation I guess but I think that this shouldn’t be a problem. Internal rotation is ok, so long as the forces are no excessive. What those are I don’ t know. I am not claiming that is going to fix “HIRD” or other issues but how much not if is usually the answer.
Unless teams are having massive herniation rates from leg swings with moderate heights and moderate swing velocities ( the hamstring length usually creates a nuchal action) I am not worries.