For the sake of the topic, I think it would have been a bad choice. Even if he had an X-Gene, I think it’s best that he was on his own. There are so many x-characters that are not in use and I think he would have been put on the proverbial back burner because so-and-such is has author stated cooler abilities. This also would have affected his cast of characters and he would have been stuck in the X-Books instead. If he did have mutant abilities, it would still have been better for him to be on his own and maybe make a guest appearance every so often with the offer to join the team on the table. If he did join the X-Men, I don’t think the character we have today would exist nor would a chunk of his supporting cast.