Divyat was not accustomed to waiting for his enemies to come up with strategies that they can use against him, every single second mattered in this confrontation and he just wanted to get to torturing those two, then killing them, or not particularly in that order. Honestly there was already a part of him that expected this to happen, Lian Rae and Lian Reed were always going to betray him no matter what.
They just simply couldn't look past the fact that he was human, even if he was the most probable option for them to follow. Even Divyat did not need anyone to tell him that he had a lot of potential, and short of completely vaporizing him, Divyat at this point was nigh unkillable.