Thats actually a good way to split a project up into closed/open imho. Open the functional part so people can see you're not sending data to hq behind their backs and make the boring time consuming ui closed. I like it. Then make money out of a service rather than the software. As we all know, tech people will see a piece if challenging software and go out of their way to replicate it and release it for free, for whatever reasons. So open sourcing that part takes the challenge away.