Actually this would work for PayPal. I believe PayPal doesn't get involved with SNAD disputes and asks you to resolve it between the buyer and seller. However it wouldn't work for a credit card chargeback.
I just checked their policy and it seems you are correct. Wow, that makes PayPal's policies seem really stupid. If I send you an empty box, PayPal won't chargeback. Buf it I can't prove I sent you anything, they will.