There's plenty of listings from individuals and small companies. No open question. Anyone can buy or sell Raspberry Pis on ebay as evidence by the thousands of people doing that.
You're absolutely correct about the presence of listings. I agree with your skepticism towards describing this as anything more than a one-off bad copyright flagging on eBay AU. That being said, the event does warrant attention to check whether it is part of broader (perhaps regional) behavior.