I guess I'd have asked him exactly the same way that you did, and then when he didn't comply... my DH would have one over to him and told him, rather than asked him, to put it out while people ate.

By then I'd have been so embarrassed I'd have taken my plate and headed back inside and eaten in the heat anyway, just so I didn't have to put up with the stench.

That's just me, but everyone is different and I know others will have handled it differently.