I read that Honeycomb source was released with Ice Cream Sandwich, just not tagged as such. Provided that source (IIRC, it was on this site I read it) was correct, it's just missing the neon lights, but you have access to it.
Also, a different way of putting the permissive/copyleft distinction is that permissive "cares" more about the code whereas copyleft "cares" more about the project as a whole. The GPL has certainly helped Linux as a project keep an identity and permissive licensing has helped get companies using a solid code as a base (e.g., the PostgreSQL forks) instead of Yet Another Flavor. Obviously, this isn't a complete picture (Android exists and there are how many BSD flavors?).