I can sympathize with him, but I think his thing about DLC characters hurting the balance is slightly exaggerated. If it's a 1v1 game (not the Capcom vs Whatever series) and the DLC character in question isn't obviously overpowered in any way, then the balance isn't hurt too badly. You'll be fighting the character if you play online anyway, so you can learn through experience. DLC will only have an advantage at the start because no one will know how to fight them properly yet.
If you're the kind of player to do a personal study on several different characters in controlled environments even if you don't plan on using them yourself, then you're kinda screwed if you don't want to pay up. That is a legitimate, if not entirely common, reason to complain about balance.