It wasn't a war specifically, it was AK getting a rake back from Stunna for all his wagered coins. Win or lose, he's still getting something for rolling at PD, on top of the leaderboard payouts.
The war predated the rakeback agreement by a few weeks. AK had a horrible run at PD before the rakeback deal was public at least.
I guess Stunna was losing at some point, and didn't want AK to lose his coins anywhere but on PD. The odds are obviously in PD's favour (what with the house edge) so effectively lowering the edge to 0.9% or whatever by offering rakebake makes sense, when the alternative is having AK possibly take his coins elsewhere to play.