Sphynx senses something malignant as he re-creates the demi-plane; but recognizing that he nor what he is doing is the cause, he does not cease his action. Having phenomenal intelligence and having once been the Champion of Thoth, it is as if he can partition his thoughts, saving one action for later. Upon completion of the spell, he switches thoughts with a sense of doom.
He knows, even before Nimbar contacts him, that someone has turned "That Wheel" and suspects it is no coincidence to the reclamation from the ill-fated future of this demi-plane. Caring not what the future holds in regard to anything within the possibility of "That Relic", he immediately opens a portal to just outside the entrance to the Tomb of Akbar.