He doesnt need a nn but you cant control what other people call him. I would think it would be a given that eventually someone at school, work, teammates, friends, even some family members would say "hey Ax pass the ketchup" or "whats up Ax?" It just kind of happens occasionally.
My nephew
Ryan we say, Hey Ry sometimes.
Kevin is
Kev at times. And occasionally Derrek is Der. I find that everyone in my family with a two syllable name we shorten it sometimes.
Kelly is Kel in a hurry,
Coleen is
Col. I just think it would be inevitable that people would call him Ax at some point.