I'm not sure how unlikeable it would have made him, at least to the audience, but I feel it would have been a stronger character moment. Worf always talks about the importance of the mission and how it's noble to die for the cause. I think he would understand and respect Jadzia's decision to stay behind, and that he might even agree with it given that this was apparently pretty important. It might not be particularly 'human' to let your wife die in order to make an important intelligence gain in wartime, but it is pretty Klingon, and Worf is a Klingon. If your alien characters aren't going to make decisions that conflict with typical human sensibilities, why even have them?