I believe the study for that was professional cyclists who are pushing their bodies limits and did very little (became sedentary) when not putting in the long hours of cycle training.
For leisure cyclists like ourselves who also likely walk about a fair bit as well, and don’t push the body’s resources to the limit, bone density is not a problem.
Sedentary people should be far more worried about bone density.
And people who to put off ageing need more than cycling to keep them strong and supple.