If you have someone in your local LW group who tells you that his utility function is that he maximizes his own utility and who doesn't have empathy that would make him feel bad when he abuses others, the rational thing is to not trust that person very much.

Intelligent sociopaths generally don't go around telling people that they're sociopaths (or words to that effect), because that would put others on their guard and make them harder to get things out of. I have heard people saying similar things before, but they've generally been confused teenagers, Internet Tough Guys, and a few people who're just really bad at recognizing their own emotions -- who also aren't the best people to trust, granted, but for different reasons.

I'd be more worried about people who habitually underestimate the empathy of others and don't have obviously poor self-image or other issues to explain it. Most of the sociopaths I've met have had a habit of assuming those they interact with share, to some extent, their own lack of empathy: probably typical-mind fallacy in action.