I just found the general combination of security - mindedness and cheap Chinese hardware curious / amusing.

I think it can make sense, since there are so often vulnerabilities in consumer router firmware, and because those devices are so common the vulnerabilities are profitable to exploit. Running a BSD-based router on a cheap Chinese PC is likely to be better security for the router’s OS and software itself, even if you don’t know for sure about the firmware on the board (which you don’t with consumer routers either, really). Overall you could still have reduced your attack surface compared to a popular consumer router.