Stallman has said some very stupid things when it comes to child abuse. I don't believe he is a sexual predator but a old odd looking guy making those sorts of comments will put people on guard.
I tend rock a similar look to Stallman and the sad reality is that people don't look at you favourably either way. I frequently get odd looks by people when out for a walk and I get stopped quite a lot by the police (I am White and live in the UK).
Simply putting on a clean shirt, some proper shoes and having a shave does wonders in this regard.
It is simpler than that. Looking clean and tidy tells other people that you take care of yourself, which is a minimum indication that you are competent.
Looks != "outlook on". The post you replied to clearly mentioned his physical looks, i.e. long hair, beard and old clothes.
I'm sure that the things you mention never had 100% approval of the left in the 1970s. In fact I've never met a leftist from that era who held those views, and I'd be quite disturbed if they did.
People should stop being ageist. If anything, sexual predators are of all ages. Especially these days when Internet allows any bored idiot unrestricted access to any number of children from the comfort of their homes.
It isn't about people being ageist. The fact of the matter is that if you look like a bit of a weirdo and you are and older guy people will look down on you and find you suspicious. It doesn't matter if you or I think it is fair or not.
Sorry that the new, rich pseudo-left with their stock options and identity politics no longer approves of that look.
So much for diversity.