Heh, it's possible.
The reality is we don't know how much, if any, communication Sisko had with Starfleet, much less what Starfleet regulations would have to say about the situation, so we really have no idea exactly how out-of-bounds Sisko was at the time. He apparently wasn't out-of-bounds enough for any of his subordinates to file a protest...or they're as guilty as he is.
All we really know is that he apparently didn't get pre-approval for what he actually did, but that could mean he didn't get approval for his specific actions versus what he did in more general terms.
It's possible, though I'll admit unlikely, that Starfleet told him, "Do whatever you have to do, within reason." "Within reason" is, of course, a horrifically vague phrase. But then, they'd probably not be as keen to say, "Take whatever actions you deem necessary."
Lord knows many contemporary militaries probably have all kinds of "extreme measures" protocols that no average citizen can or would want to know about.