Damar might've offered the alternative that Gul Re'jal's Cardassia needed: a middle way. A leader who can work with others but is strong enough to hold his own and not be a puppet. (He's already been down that path once, and he won't want to do that again.) But really, do you think Re'jal would have a "good guy" character backing her version of Ghemor?
At least that's my unofficial opinion.