well, enemy AI for sniper would probably choose the worst possible result for you, which would be the cargo with the most dots but less than their total damage that isn't plated. Also, pyro sounds crazy with birds (unless you explicitly don't allow that combo to work)
Well burned cargo is not affected for birds, it only deals damage to the surrounding cargo at each of the turns so it wouldn't be like rigged cargo which is crazy weak. Also, burned cargo is immune to burn damage from other pieces of burned cargo so infinite damage loops don't happen. Also your suggestion of the enemy Sniper A.I is good