It was a perfectly human reaction, and it fit Sisko's character at the time. He was still angry, bitter and hadn't realized how far he'd fallen as a person. The whole Prophets thing made him realize he had to let go and accept what his life had become, accept pain and loss as part of the human experience, etc. The novelization of Emissary made it clear that Sisko felt awful over how he treated Picard and realized that Picard was just another victim of the Borg and didn't deserve any hatred from him.
I don't think Picard had any right to 'chew out' Sisko for being pissed. I mean, Locutus was responsible for Jennifer's death. I think it would be hard for anyone to completely separate Picard from his actions as Locutus when they were such an up-close-and-pesonal victim of those actions. If Picard didn't know and appreciate that, then he has no conscience at all. Yes... I think the conversation was intended to pass the baton and perhaps put a bit a distance between the two shows - give DS9 it's own identity. But asking Sisko to just forgive and forget without even a comment or attitude would have been pretty unrealistic, so I think they played it just right. For Sisko to just forgive and forget without struggle would be like a murder victim's husband in our own day, just forgiving and forgetting a criminal who had murdered his wife just because that criminal was found insane. It's hard to do something like that - at least right away. Getting to forgiveness can take a long time.