Originally Posted by
Obelisk Kai
Look, here is my take on it. Make of it what you will.
The Seat of the Pantheon did not just 'happen' to be in proximity of Argus. It is clearly a structure of great importance to the Titans as a homebase and it is moveable. Sargeras likely moved it to Argus following the defeat of the Pantheon with the possible hope it would be used as the base for his unstoppable Dark Pantheon once he had finished corrupting them.
I suspect that the Seat of the Pantheon has a recall sequence that each Titan could use to rapidly return to their home base to communicate with the other Titans on matters of great importance.
Once the sequence completed, a normally planet sized Titan would be resized to the dimensions of the Seat automatically (I think it's obvious at this point the Titans are able to adjust their size if required, but the power remains the same. That must be why they required minions on Azeroth during the War against the Black Empire rather than doing it themselves, their power would still be too dangerous to the planet on ANY scale. It also explains why Brox was able to 'wound Sargeras'. Sargeras had scaled down in anticipation of entering the well of eternity portal)
What the Titans seem to have done was forcibly activate the recall sequence on Sargeras. This brought him to the Seat, where the technology of the titans will keep him there forever. After all, should he try to leave, they can just use the recall sequence again and he is no match for six other Titans, each as strong as he is, at the base of their power.