Safety of neck harness training?

Whats the BBM take on direct neck training? I do plate neck flexion and harness extension on GPP days for aesthetic gains, it grows fast as hell with direct work.

Do you have anything against this other than the fact it’s not necessary for strength?

We don’t find it particularly useful for our purposes, though it sounds like you’ve identified something that seems to work well for your goals.

I doubt there’s anything inherently dangerous about the exercise. I’d hypothesize that any injury risk is mediated by the same mechanisms observed for any other exercise - primarily, inappropriate loading / progression.