You mean, for their motives? Yes. We do that every day. "Motives" are not protected free speech. They're a way of determining the reason something negative happened. If he had simply developed the software as a tool, that's one thing. To market it for the express purpose of illegal activity is another.
If you own a gun store and sell people guns that may end up being used illegally, that's fine. If you own a gun store and sell a gun to someone that says they're going to use it for illegal acts, that's another.