I think he says that he would take the ring out of pity for the hobbit. He talks about the weakness of the hobbit (being a small and fragile creation) which would make him (Gandalf) want to help him out of pity and his personal desire to do good. However, he knows taking the ring would also corrupt him, and only the innocence of the hobbits can carry the burden as they themselves are as corruptible as he might be.