Remember one of the Weyouns was willing to kill Odo. Vorta are clearly more capable of independent thought than the gem'hadar, that's why they were given the leadership and diplomatic positions.
I think the most likely explanations are either she had a specific genetic enhancement, or she had a device on her.
Or the real explanation is probably that the writers just didn't like it, but that's the plot explanation.
Well Weyoun(8 was it?) was very reluctant to do it. It took a combination of Damar pushing it along with saving his own butt(knowing how replaceable -he- is) to get him to give that order. Even then, he backed away from it at the first chance.
Though yes, Eris maintaining her cover and the Founders secret identity would seem to be more important than bowing to a god who doesn't even know he's one.