erato, love and respect the alliance, but...
However you want to define it, a city changed hands. Only two reasons to keep an inactive member within the alliance: you plan to take his cities or he will be back soon to play on as before. If you plan to take his cities, support should have been there to create reports of the attack and defend as needed (we get BPs for support now, of course, kinda mixed feelings on that) or if he is coming back he now has city slots to plan around. Either way, DY lost, The E gained. At this stage of the game it is all about BPs to expand anyways, neither side will knock a player out of the game unless boredom sets in or RL has to be addressed...
Most importantly, make sure you are having fun, no reason to waste time on this bs if it isn't enjoyable