I mean...I guess it'll go in a good direction with someone learning quickly. But, the start. Wow, that's painfully stupid. Taking his title because someone in the future might surpass him? If there is no one greater than him in that field of magic, he deserves the recognition for it until someone surpasses him. If anything, the story would have made more sense with him ruining this group's reputation and public trust by using this action against them. He could even have used his high potential to master the rest of the magics listed and if they refused to recognize his skill in them due to him challenging them on the red magic thing, he could use that against them as well with great effect. After all, if he's proven himself far and wide, all that their rejection would do is cause everyone to reject them back. They'd be ruined.
Heck, even their own argument would be disproven by Zeff himself being the greatest red mage. If the potential thing mattered so much, he wouldn't have reached that point. Yet, he did.