Let's be reasonable, there's just something you can't just overlook. And not everyone is going to be willing to forgive and forget.
That's the problem with comics characters crossing a line like that. When they're inevitably brought back into the fold, it's usually "All is forgiven, let us not speak of this again" (about a half-dozen Batman misdeeds) or "We'll say all is forgiven, but we'll throw your misdeeds back in your face at every opportunity" (Hank Pym: Wife Beater*)
The only time I can think where this sort of thing was handled without jumping to either extreme was in Justice League Unlimited, where Hawkgirl was allowed back into the Leeague, and was met with open mistrust by most of the league.