He knows that he *can* do something with his powers, but he's in the same possition Claire is at this point and it's an echo of her "I can climb through a woodchipper and live to tell about it" rant. They both are more focused on the huge potential for their powers to ruin their lives and their families (potential made actual in Nathan's case with the accident), that they can't focus on the benefits or world-saving-ness of it at this point like Peter and Hiro can.

It's another neat parallel between them. The other ones I notices is that Claire, no matter whether she thought Jackie was too mean about what's her name, was ambitious enough to not only genuinenly want to be a cheerleader but to dump Zach as a friend after they used to be close as kids. Her "I'll even talk with you in public" promise as a reward in the pilot is pure condescending Nathan in political mode. And of course both Claire and Nathan are convinced that discovery of superpowers would result in disaster.