The fact that Ephi has yet to give a reason to this, is either that he was in a hurry or most likely for personal reasons. Steam seems to have little effect on this event.
He is probably moving from development of the RTB network to things that might seem more important to him in the real world and such, and shutting down the majority of things would prevent frequent attacks, exploits, etc. which would be striking up drama (not necessarily the forum section) that could go ongoing while he's absent.
Though these are just assumptions until a real reason is uncovered
that or this is some huge prank.
