If Sisko's decision leads to a war with the Romulans that proves more devastating than the Dominion War, would it still have been the "right" choice?
How can a war with a technologically equal race end up being more devastating than losing the Dominion war and having thousands of Jem'Hadar soldiers on every Federation planet?
I simply don't buy it. Plus, drawing the Romulans into the war would also have the benefit of depleting their resources and ability to make war. If the Federation was able to somehow come out victorious against the Dominion on its own, it would be so weakened that it would be easy pickings for a Romulan Empire that sat on the sidelines.
Which is not to say that there wasn't risk of blowback and negative consequences down the road. It was a messy, complicated situation that didn't lend itself to simple, black-and-white considerations of right and wrong--which was entirely the point of the episode.