Is the Menno / Blackface thing the full body suit and nappy combination? As opposed to "normal", "make-up" blackface?
Seems a bit (very?) misguided of Menno, but not 100% sure I call it blackface.
FWIW I think of blackface like womanface. I don't believe that it is right to say that a white person pretending to be black is always wrong, I believe that very occasionally it can be done in a way that is not massively offensive to black people. I would, for example, find it very hard to criticise as theatre company who were making an anti-racist play featuring a racist white character who is shown up for his bigotry and stupidity after turning up on a stag do in black face.
Just like men who dress up as women. I am not going to say that every single drag act and trans woman is a deeply offensive misogynist - I am sure that on occasion men play at being women in a way that is not deeply offensive. If an all-boys school decided to put on a sixth form play celebrating women's acheivement in science and respectfully portrayed a series of female scientists using the only actors available - male ones - then that would probably be OK.
Also worth noting that one can put black make-up on your face without it being blackface (eg white soldiers mights smear black make-up before a night-raid). Likewise men can have long hair or way make up or even wear dresses without it being a parody of women (eg I don't think Kurt Cobain ever looked like he was presenting as a woman, despite having long-ish hair and often wearing make-up and a dress).