I don't think any reviewer of the paper would ask why they didn't use one the processors mentioned. I think of lots of reasons to do it with a riscv * lot

I don't think any reviewer of the paper would ask why they didn't use one the processors mentioned. I think of lots of reasons to do it with a riscv * lots of excellent simulators and emulators * great tool chains * both software (Verilog, VHDL) implementations as well as hardware * regular, compact instruction set (no condition codes) Using anything besides RISC-V would have been an order of magnitude harder.