Sauron did not worry too much about it. Although Polylegs were timid and changed their minds easily, Tatamu had been with Sauron for several decades. It was diligent and very loyal. There had never been any mishaps when he entrusted it with something.
After Sauron left, Tatamu immediately sealed the door of the laboratory. The door was thick and heavy. It would take some time for anyone to break through the door. Tatamu would have more than enough time to activate the arcane array.
