The issue is not height per se, but where the body center of mass (gravity) is relative to the bending pivot point, typically where the lumbar spine joins the pelvis. Someone who is tall, muscular and lean will have a high torque exerted on the lower back and pelvis, as their COG may be in the chest, creating a long torque arm. Someone who is of the same height, but more of a lard ass, will have the same length torque arm, but their center of gravity may be around the pelvis, comparatively lessening the torque on the pelvis when bending. It is one of the very few situations where suboptimal conditioning may be an advantage. Pass the doughnuts, please.
Women have lower centers of gravity, which may be beneficial when playing pool.
If you look at the fit male pros with the V shaped bodies, observe how they shift weight to their bridge-hand forearms whenever possible, providing more support for their high centers of gravity and reducing low back stress (while improving stability).
What can be done for the player having low back stress issues?:
1. Bend the knees a little, releasing the pull on the pelvis from below
2. Try to get your center of gravity over, or at least near to the line between your ankles
3. Use a supportive bridge hand/arm when possible
4. Minimize the time spent down on the shot
All of these have their downside, but if you want to minimize low back stress, it is the kind of thing that needs to be done.
Willie did pretty good with it. 
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