That's kind of brilliant. I had no idea that kind of thing would actually work. I always assumed that bidirectional connections were needed to allow ETH frames to function, electrically. I further assumed this applied to optical networking too.
For 100BaseFX and 1000BaseSX at least, there’s no auto negotiation for link speed etc. As long as it sees a carrier from what it thinks is the other end of the link, it’s happy.
