They could easily be in separate rooms, in separate parts of the building. That seems like a minimum precaution. What if there was a normal fire? What about a normal power outage? What about a normal sprinkler system discharge?
It doesn't take a lunatic to disable 2 server racks in the same room.
Also from the article it says water damage to equipment which made it sound like they didn't have inert gas fire suppression systems installed (or that it couldn't handle the fire).
It doesn't take a lunatic to disable 2 server racks in the same room.