I get your point, I really do. It's a decent argument, but if that's his gasoline, let him use it. Motivation is a hard thing to come by and his story just illustrates how hard it can be to focus and build something when dealing with emotional issues.

I don't think it hurts anyone when he says he's helping solve cancer, he's not stealing anyone's thunder. There's plenty of evidence of tool/library developers not getting any credit in the end product. If someone directly finds a cure using Light Table as their IDE, I'm pretty damn sure not a lot of people are going to seek out Chris and congratulate him on curing cancer. But he would've helped and that's the important thing. So let him have his motivation and keep building things.