When Veldora was in Rimuru, he regularly supplied Rimuru with magicules allowing him to go on naming sprees. Without Veldora inside, can Rimuru name frequently without long term loss in magicules? Rimuru has tons of magicules after evolving into a Demon Lord, but that doesn't mean he'll recuperate his magicules quickly after giving names anymore. Most people don't given names frequently because of the long time it takes to recuperate the loss in magicules.
Of course he can go on naming others. If he is about to run out of magicules he can use his ultimate skill Beelzebuth to absorb magicules from the surroundings.