The decision of who was made councilor isn't a "big" decision like others. I mean, you decided who would become councilor at the end of ME1, and then in the beginning of ME2 you could change your mind. Besides, the role of the councilor made no difference what-so-ever in ME2, except that you'd get a different cutscene.
If the citadel and the council had played a larger roll in ME2 I could see the change being rage-worthy, but in its current incarnation, it's a pointless decision with no effect on the game at all.
Anderson resigning and returning to the Alliance military in the face of a Reaper invasion makes perfect sense.
I thought if Udina had became councilor in ME1, he wouldn't reinstate your Spectre status in ME2. I think that's what I read somewhere. I do not know this, since I could never bring myself to choose him. How big of a difference this made, I couldn't say. Just looked like a few dialogue wheel choices between, "I'm a Spectre," and "I'm with the Alliance," and "I'm Shepard." when introducing yourself.
But, Anderson resigning to take up arms on Earth was the logical choice for ME3 no matter who was councilor... but to be quite honest... I think Anderson should have promoted Bailey and gave Udina a few more belly punches... you know... for old time's sake.
Check your codex. It explains how Anderson retired as a councilor in favor of military life, if you chose Anderson that is.
[Edited by poster55, 3/9/2012 2:31:59 PM]
If people are going to say this just go do that outside of these forums or actually post what it is saying in the codex! Other than that. I do not really care why he came back. I can not even see why you would want some one who is more military in politics placement. Thats just mental.