I'm aware of the google case, but "ownership" of ISAs seems to be a settled thing. That's partly what ARM's business is (i.e., to license the ISA to Apple for example). Do you have a clarifying source on copyright v/s patents regarding ISAs? RISC_V would also not be so significant if it were just a matter of running out patent clocks. MIPS is quite old too and would have expired soonish by the same logic (MIPS's own open-source announcement notwithstanding). Intel has also been passive-aggressively threatening MS and others legally so that they don't emulate x86 on ARM hardware. I remember when MS showcased some ARM laptop, Intel Legal sent out some press briefing claiming how they'll protect their IP. Qemu gets a pass though since it's non-commercial and there is nobody to sue. It would also be bad PR.

Edit: You may be right that it's only patents afterall and not copyright. This was Intel's briefing:

"However, there have been reports that some companies may try to emulate Intel’s proprietary x86 ISA without Intel’s authorization. Emulation is not a new technology, and Transmeta was notably the last company to claim to have produced a compatible x86 processor using emulation (“code morphing”) techniques. Intel enforced patents relating to SIMD instruction set enhancements against Transmeta’s x86 implementation even though it used emulation. In any event, Transmeta was not commercially successful, and it exited the microprocessor business 10 years ago."