In the context of a DEI training, that seems like a more of a training issue, not a non-black-people issue. There are plenty of ways to get broad participation, if that's what's desired.

Maybe it's cathartic to complain about it on Medium--and that's fine--but a lot of companies have a lot of trouble with DEI training not working in various ways. In particular, it's really hard to develop a feeling of psychological safety, and if you don't have that, nobody is going to budge much on any perspective and nobody who might be threatened is going to say much, because you need safety to do either.