I wish I could find this picture right now, but when Chanty popped up on the scene they did it with blackface. That's what turned me off the band entirely. But did they mean anything with it? Probably not, because they live in a pretty homogeneous country and they don't have the cultural conditioning to understand why it is wrong. I would say they lack that conditioning so much, it wraps around the continuum and becomes something so foreign to them that it's not even shocking. Does that make any sense?
I agree with some of the points you made, but not with the conclusion. People do edgy shit all the time for attention. That doesn't mean they actually believe what they're doing. Visual kei bands appropriated nazi imagery years ago, but that doesn't mean they are automatically all neo nazis. Most bands have never appropriated this imagery, so by your logic most bands aren't neo nazis! We're going to need Akane-level outbursts on twitter saying they hate gays, jews, and blacks, or lyrics or interviews that say as much, before I would be willing to point to a band member and say "yep, that's a neo nazi right there".
If you wish to educate us some more, exactly who is it that you are thinking of and what proof do you have? Proof is the coin of the realm here on MH.