I'd agree - damp your side of the fence as a precaution - they know you are unhappy, and may feel it is OTT, but it would reduce the chance of damage on your side, and if the fence did catch, slow flame progress while you are making a 999 call, so the bonfire can be totally drenched and neighbour given verbal reprimand.
Is this a semi-detached where this neighbour's home joins yours?
Just that it seems that while the guy is a fool, he did move the bonfire. If it ends up needing Fire Brigade, you did what you could to explain your qualms and they might not be complete dumbfucks in future... having had his daft idea completely trumped (if FB is actually needed).
You are taking the risk seriously. He has compromised a little. If it still goes wrong, he will be feeling a complete twat (and if FB are needed, will probably be warned not to do it again).
On the one hand, I really hope the FB not needed (for your sake) but on the other, if they are needed, he will feel such a dumbfuck, he will probably take note if given friendly advice in future (and hopefully some consultation will go on if there are ever any plans for an extension, etc, rather than blunder into it and then have you object on really sensible grounds, and have council take your side)...
Best of luck.
PS My cat just decided she wanted to come in (she is usually an outdoorsy madam unless there is a gale blowing) but a few noisy fireworks and food and warmth tempted her.
Yesterday night a local(ish) scrapyard had 12 cars burn and gas containers exploding...
I only noticed there had been something happen when my local transport app showed the trains were cancelled for 3 hours (I don't bother with Twitter or FB), and the bangs, even if audible here, between 7pm and 10pm, would be lost in the assorted whistles and bangs from fireworks closer to me.