I would have left him there to wash dishes, pay for my meal and go home and watch a movie! It's not a loving thing to do to save someone's from their irresponsible behavior. If he doesn't have the intelligence to think that he is going to need money when entering a restaurant he can't be intelligent enough to have a relationship with.
Some may call me a proper b&stard for this, but i did just that with a date who told me she forgot her wallet after she ordered a lot of drinks and food.
I told the waiter were paying separately after this revelation and promptly paid my part and left her to it.
First date as well, also my last with this particular person