This actually seems like the most reasonable reason to me. It wasn't stable, there was nobody (planning) on making RISC-V devices on which you'd want to run And

This actually seems like the most reasonable reason to me. It wasn't stable, there was nobody (planning) on making RISC-V devices on which you'd want to run Android, and compiler support was far behind. We're in a very different place now, I would have made that same call (though perhaps would have given more reasoning to reduce speculation).