Jones only won the primary because nobody else bothered running for a district that is guaranteed to go Democrat anyway. If there had been *any* other candidate Jones would have lost. So the only way to stop something like this, if you care to, is to make sure someone is running in every district, even if it’s completely futile. Do you really think it’s worthwhile?
The main point is that the GOP has no control over this, and is not responsible for him in any way. He is not a Republican. Once nominations closed there was nothing the GOP could have done to take him off the ballot.