There is another option. Sell the compiled gpu kernals in a binary format:
(Like wolf0's sgminer .bin files)
This will be linux compatible, and the user can use a modified ccminer without gpu-code.
No Licesence issues, if the kernals are written from scratch.. (They should if you want to optimize them)
-- SNIP--
Dynamically loading non-GPL code into GPL code is legal grey area. Not that there's any precedent for any of this stuff.
It also does nothing to address the issue of the fee being removed.