I wouldn't call it metagaming. I actually find I respect those opponents who do everything they can to try and keep their nation alive, rather than just roll over as soon as things start to go poorly for them. And fighting a defensive war when you have no chance of winning is actually quite fun and a good time to try new tactics and learn. Bane venom charms are in the game for a reason and are a decent tactic to damage your foes economy and disease their mages - burning down labs and forts weakens your foes so if you get allies to help they have less chance to strike back. I don't see these actions as having "no reason". So IMHO it is not "bad manners" at all, but playing the game to its fullest. For me it is more of a metagaming issue to start off a new game perceiving someone as an enemy - that is something I never do and I consider to be bad manners.
Anyway, Agartha shall soon be gone. Hats off to Pythium - they were a worthy foe and we wish them well in their struggle against imperialist impression.
