So if someone were to design a variation of that item that is actually at least 36" long, would it then be allowed? I think he missed the actual underlying issue of that question.
I also think it should be possible to design one of those with variable retractable positions for different speeds. I'm sure it would be difficult to get to any speed resembling a pro's "hard" shot, but I suspect it could support any shot from super-soft up to about medium.
And, if nothing else, the existence of this product supports the idea that 90%+ of success in cue sports is having a repeatable, straight stroke.