This is a ton of agita over $50.
If it were me, and I thought it worth shipping 4 oz of tobacco halfway around the world a SECOND time, I guess I'd refund him and ask him to ship it back. If you are worried, given it is going to take a good while to get here, ask him to ship some way that has tracking, then when he send the tracking, send him the money.
If you get back an empty jar, it's $50. (Think three cob pipes.) If you get back the full jar, well, even steven.
But really, what is your time and psychic energy worth? And is this how you want to spend those precious commodities?