In Linus' case, there is reason for people who don't follow Linux closely to think he is part of the "disgusting underbelly".

A few people I know, when discussing this story, know Linus mainly as the Linux kernel developer who writes long insulting e-mails to people who's posts he doesn't like. The "retroactive abortion" seems particularly famous.

I'm not saying this is fair, given the massive and positive effect of the Linux kernel, but that doesn't stop it being true (based on my tiny sample).