Yeh, one of the problems in dealing with this kind of issue is that the Constitution does not provide for any process to recall a Senator. If it did, he would be within his rights to just say "I am staying but will of course abide by the outcome of the recall- period- so FU senators, I don't care what you think because this is between me and the people of Minnesota."
I do think though that the dems who are thinking that if they can toss or drive out Franken that that gives them precedent/bitching rights to drive out Moore. Because the Constitution does not have a recall process for senators, it gives the Senate the power to expel not only to get rid or people who are a problem in the senate but to protect the people from the state he represents who would otherwise have no way of getting rid of him if it turns out he is monster after he is elected. But that is tough argument to apply to a senator who was elected by people who had full knowledge of his bad behavior and stills said that he was their choice. It was not the intent of Framers to have the Senate replace informed voters with their opinion of who would be better. To not seat that senator or to try to remove him is absolutely at odds with the constitutional power of a state to have their duly elected representatives seated.
Moore and Franken situations are similar on the surface but big, big constitutional differences underneath. AS MANY ARE ABOUT TO FIND OUT.