One point worth remembering is that when Alexander was summoned, it calculated out the outcomes of every possible timeline, including one in which it intervened to prevent the Seventh Umbral Calamity from ever happening. On review of all these, its final judgement was to preserve the existing timeline and remove itself from it by creating a time loop. By that same logic, you'd think that people would hold it responsible for all the bad things that ever happened in the universe, but people generally don't perceive things that way.

Most people don't enjoy being caught up in wars, and someone really keen on fighting rarely needs a good reason for doing so anyways. Mid seems like he's got much better things to be doing with his time, like taking cat naps in aetherically dense areas, and I can't fault him for that. Someday, when we retire from adventuring, I would love to go on a tour with him to visit all the top aether hotspots around the world.