Wolf 359 was Starlfleet's fault anyhow. they let one Federation ship face a near invincible Borg cube lol... Picard's capture was thus inevitable, since he could only do a certain amount to prevent capture. And the Borg evidently had that plan all along (that Borg Queen is very cunning lol..) so Starfleet played right into it. Somebody told me once that Picard could have had more officers on the bridge to prevent capture. lol.. I don't get how that would have helped. Yes, more Borg would have been killed, but then they'll send more drones, these drones will adapt to the phasers, and physically overpower all officers present. Only Data would not be overpowered, for obvious reasons. Even placing a forcefield around Deck 1 is no use against the Borg. Against the Romulans or the Dominion, maybe, but the Borg is a higher level all round lol..
So I don't believe Sisko's treatment of Picard was fair, but I agree it was understandable.