^ I think it's fair to say that there wasn't a lot of time for Garibaldi and Sheridan to have a heart to heart, hug, cry and burn an effigy of Bester together. Lyta verified his story and his part in rescuing Sheridan and the liberation of Mars probably went a long way to re-confirming his reliability. It may have taken Sheridan some time and effort to swallow any involuntary emotional resentment, but in all seriousness I doubt they're the sort to talk about it directly.
Actually, if you look at Garibaldi's actions throughout the first (mostly sober) half of season 5, it's clear this is a man trying to make amends. He puts his life with Lise on hold (again!) to go back to B5 and lend the Alliance his support. For Sheridan's part, it's not exactly the first time someone he knew turned out to be brainwashed. Not even the second time, so I'm sure he dealt with it pretty fast.
Resolving the Earth civil war could be seen as one step towards gathering enough forces to fight aganist the Shadows.
I rather think it'd undermine the drama and peril of the situation. The whole point of the Earth Civil War storyline was to have the station cut off from Earth and any support. They were out there on their own and were forced to stitch together an alliance of disparate and in some cases mutually belligerent races. That wouldn't have happened after EF rolled back into town.
Although Earth essentially sat the war out, humans were still at the centre of the Shadow War. They may not have made up the bulk of the military forces, but they were *central* to the logistical support, intelligence and command infrastructure. On top of that, humans were the ones that brokered the alliance in the first place. So what if Geneva had nothing to do with it? Also don't forget that there are plenty of humans that don't actually live on Earth, or even in the Sol System. There's dozen a colonies and non-military outposts scattered around the place that it seems Clark's regime just abandoned. Remember we later see Garibaldi reunite a father and daughter who where separated when a scavenger fleet took advantage of the chaos of the war. I'm sure there were plenty of humans right in the thick of things that we never heard anything about. Indeed we never did hear on the show why the Shadows hit Arisia III (an Earth mining colony) so early on, way before they started attacking openly. I'm sure they did a lot more we never heard about.
In fact, if I had any criticism of the 4th season it'd be that you never got a real sense of the scale and scope of the conflict.
I'm not saying having Earthforce on their side would have won the war, I'm saying it was symbolically important that they represent the new age of life in the galaxy.
What would Earthforce have to do with heralding a "new age of life in the galaxy"? If any human military force could even remotely answer that claim it's the Rangers, not Earthforce.