I know it may upset Picard fans, but Sisko didn't need to apologize to Picard for how he originally felt--he was just being honest. For three years, Sisko had been grieving over the loss of his wife and he then meets the man whose face was forever etched in his mind as the architect of the worst moment of his life. Sisko can't just smile and pretend that it didn't happen--and Picard knew that too. Sisko had yet to undergo the journey to put that pain behind him and start living again, and once that was complete only then
could he see Picard as Picard rather than Locutus.
Heck, I imagine that there are still
many in Starfleet who aren't Picard fans because of his time as Locutus, but at least Sisko got over it.