I think Sisko knew that involving Garak was a risk but that he also didn't feel he could involve anyone else, and he didn't consciously expect or anticipate Garak's Plan B.
I think in part he's angry that Garak didn't tell him what he was planning, even as I'm sure another part of him is relieved that he can take comfort in the fact that he didn't know what Garak was going to do.
It's funny to think that if it was Picard in command of DS9 then the AQ might have lost the Dominion War, because it seems far less likely that Picard could have brought himself to dirty his hands in this manner.
I think in part he's angry that Garak didn't tell him what he was planning, even as I'm sure another part of him is relieved that he can take comfort in the fact that he didn't know what Garak was going to do.
It's funny to think that if it was Picard in command of DS9 then the AQ might have lost the Dominion War, because it seems far less likely that Picard could have brought himself to dirty his hands in this manner.