I feel the need to point out that, since all RP interactions have an outcome that is based on the players involved agreeing on it, the weapons used in the RP have no more than a flavour value. You could win a battle against me with sticks and stone if I agree with it; on reverse, you could built a Death Star and fire on my island but if I don't roll with it it simply doesn't happen.
Bottom line: wheter you develop chem weapons or not has no influence on the results you will get in the course of the war.

That said, if you want them for lore reason you should definitely get them, knowing that it will have of course effects in RP.
Bruuma being an evil dictatorship for example means that nobody will question my using of chem weapons - since they already think I'm evil -  but it also meant that nobody joined my side in the war and all joined Erinor.