Maybe using an ARM dev board boosts acceptance of this book among its target audience, at the moment. But, for open source hardware goals, a RISC-V board, such as the HiFive1, would be good cross-promotion/support.
Imagine Rust being considered the way to develop for embedded RISC-V, from almost the start.
Similarly, as long as Rust is already shaking up C/C++ a bit, they could nudge some hobby/education and professional development towards RISC-V. (Especially on embedded, right now, as I've heard the open ISA is attractive to some projects.)
