I spent a lot of time on SSC from 2013 to 2017, and my recollection is that the Venn diagram of commenters promoting HBD and those promoting RDx was nearly a circle. And similarly for related sites like LW. So in that context I would say the two are closely related.
I find it hard to believe you've been exposed to much NRx content if you don't think they consider HBD true and very important. Although don't take that as a criticism -- I would not recommend wading through their beliefs and look back on it as a waste of my time.