This would be fine. The only time healing powers in the various Storybook/Alice Worlds would be unallowed would be when they'd revive someone or heal them free of cost. We try to make sure everything has at least some cost on the characters, since the World itself wants to ensure it's pushing against them.

A thing to note, though: since death in the Worlds is actually impermanent, the healing powers would by and large end up pointless. The characters themselves likely aren't going to realize this at first, unfortunately, so he's free to use it as much as he likes.

It would not, however, work on any NPC or riddle-based challenges where, say, a denizen of said World was hurt and required something else from the World to be "fixed".

I hope this answers your question! Let us know if it doesn't.