This studies suggest that it does protect (in mice)..

https://www.ncbi.nlm.nih.gov/pubmed/17243547

In humans, it's really only been proven to work safely in post-menopausal women. I would think that, in theory, a man with zero T should also benefit from it, but there aren't enough eunuchs to perform widespread drug testing on to have statistical confidence about.

Studies done on men with prostate cancer undergoing ADT show that it does protect from bone loss.