Shaq is extremely sensitive and can't take any criticisms/jokes. Even on TNT, every time someone makes a joke about him or something, he defaults to bringing up his rings. I respect guys like Charles Barkley, Kenny Smith, etc. who have no problem taking a joke even if the joke is about them.
Shaq is just one of those guys who can dish it, but can't take it.
Now Dwight Howard also has his history, I get it. But Dwight doesn't even say much to Shaq directly either. Shaq just hates that Howard uses the "superman" thing but it's becoming a weird obsession.
I think Shaq would be better off just not talking about it anymore even if he has the urge. Howard's basically done in the NBA as is, and basically just off everyone's radar.