The novelization of "Emissary" makes it clear that Sisko realized what a total jerk he'd been earlier and when he saw Picard again at the end he felt ashamed about it and realized he and Picard were both nothing more than victims of the Borg.
Exactly. They were both victims, so I just don't see why there's a side to pick. Sure, after the wounds of losing his wife weren't fresh, he could afford to have some empathy for Picard. You could say he wasn't fully himself when he had to see and take orders from the man that murdered his wife while the wounds were still fresh because the truth is (and I know from having been there) that you are definitely NOT yourself when you are grieving, even if you are able to function and do what is necessary because you have to press on.
So if people are able to understand Picard not being himself, then I wonder why anyone would have a hard time with Sisko. I don't know. Maybe if you don't know what that kind of losing does to a person and how they carry it (just like Picard has to carry his guilt) with them, and it doesn't ever fully go away, then it's easy to only see one side.