but lets be honest, the difference between nvidia and ati hardware isn't that wide, they have already looked at your chips anywyas.
These are all exscuses. silly ones at that, It would be easier to prove corporate espionage at such a point to. You not protecting your IP. If I had enough time I could figure out how to program for my video card. I just don't have the time to invest into the effort. the first thing I would do is reverse engineer the bios. then I'd start poking at the hardware to test for functions. Likel I'd automate this process, in the span of a month of two I could get 99% of the info I needed about your chip to write my own code. I don't however have the time.
Truth is, you competitor already handily disassembles your code and you hardware. You do it to.
copyright your chips and the tech in them. Thats how you protect your IP.