For instance, people with neutral players (AI neutral) at borders will not need to disturb them and they will not pose threats until attacked - so people with bordering neutrals can easily focus on live neighbors. But, if there is neutral AI that can attack if he sees weakness in your defense this is different story.
this is already the case for the current situation of diplos, AI or not; if one player's neighbour gets booted and goes neutral, he will of course focus and stack more on live neighbours. Implementing an AI will barely change this, if at all.
If players that are booted get back, they will have cumulative armies that were not used in clashes, thus they will be in better position than people who play continuously.
there's already a solution for this if wanted, it's called "army cap".
Overall, I still believe there should a passive AI for diplo games that only deploys on fronts. While having a "diplomacy" gamemode is of course something all diplo players would ultimately want, it doesn't necessary have to be immediate; the condition of diplo games could already increase dramatically by making simpler updates like this one or with some uservoices ideas(like https://warlight.uservoice.com/forums/77051-warlight-features/suggestions/5702941-auto-deployment-in-one-territory-bonuses-when-play
) without totally changing the WarLight engine to add a new gamemode.
Edited 9/5/2016 21:41:15