If it works, do it.

The body is so much more complex and cool than studies can ever convey! If you feel better and if you function better, you are better!

It would make perfect sense to me that something helping cartilage repair/generation would also help in a situation with a frayed supraspinatus (I assume that's the one) tendon in a rotator cuff.

Supraspinatus is in charge of sliding the head of the humerus DOWN as the distal end of the humerus elevates. Joint not slippery enough, the frayed supraspinatus can't slide it. (too much friction for the diminished tendon)

If it works, do it!

As one of my instructors said (again and again and again) "it is what it is." If it works, it works.