This is also true with ARM, which is why I doubt RISC-V is a solution to the problem of bad firmware and/or lack of SoC documentation. ARM is "open" in the sense that the CPU architecture is publicly documented --- you just can't legally implement the CPU without licensing it from ARM.

FYI the pre-Pentium subset of x86 has been public-domain and free of patents for a long time, and I believe several more Pentium-level patents are going to expire soon, so in that sense a lot of the basic x86 instruction set is more open than ARM. No doubt if RISC-V becomes popular there will be plenty of proprietary extensions to it too.