Kato-2
Put yourself in Chinese shoes, imagine RISC-V products become mainstream and are used wide-spread in society.
You would have to be an extremely naive person to think the USA would not manufacture RISC-V clones of existing products but with hidden payloads and try to insert them into critical areas of Chinese society. The USA spies on its own allies and bugs European governments (caught doing it more than once), imagine what they do to rivals.
So having their own instruction set does make such scenarios more difficult.
Erm, what??
If you are worried about clone products, well really they just have to look the part and not much else. You could build a clone machine with an ARM chip in it, and as long as it behaves to the outside world like the original you would go undetected. It would just oddly get bricked if you uploaded new firmware.
But basically the Chinese can remove all US influence by:
They take the pdf describing the RISC-V instruction set. They print it out, and read it.
They design a RISC-V compatible CPU.
They are currently writing their own compiler back ends, they can still do that.
They are doing their own OS porting onto their CPU, they can still do that.
So they lose nothing by following RISC-V design rules, because they are just an instruction set definition and in that respect cannot hide anything.
BUT, if they went RISC-V then they can run a standard Linux kernel. They can sell chips to people who want to stick with the GCC or CLANG compiler chains they love. Some people will shrug it off as a spyware riddled Chinese device, but the option is there.
I cannot imagine buying a new CPU design these days. There are already plenty to choose from and it takes years for development tools to settle down to being really usable.