I don't think it proves anything. Many (most?) of male SJWs on Tumblr are gay, they wouldn't feel attracted to her even if she was 300kg lighter. I constantly tell ugly, non-fat people I know they're beautiful and that they should be confident in themselves. But that doesn't mean I want to fuck them, it just means that I don't think that person should be depressed about their own image. If I want to fuck them, I'd say they're hot, or sexy, or invited to know my new house.