They still don't have the same goal as the Thalmor though.

Say this OP! Selrahc Rorepme

Only getting a Thalmor to say his name backwards can send him back to the fifth dimension where he belongs.

We actually don't know that, the Altmer aren't the only ones who gain immortality from the unmaking of Mundus, all souls do its just they want to purge all the races that worship anything pandoimic or honor lorkhan/talos so that Mundus can't be remade.

In TES, none of the races can claim to be the good guys. It is all a matter of perspective. Maybe except the Orcs, who have been majorly screwed over ever since the HoonDing did them in.