A Quinton has a +32 Listen check and a +28 Sense Motive check. His Intelligence is over the roof.
He is not more that a meter from MitD when it plots to hinder Xykon's efforts.
If Quinton was somehow interested in results, he would tell MitD to not act, or inform Redcloak, or even declare MitD an "hostile" and block it himself.
As it didn't even comment on MitD's resolution, I'd suppose that Quinton is fine either with Xykon to fail, or for him to have an hard time.
I personally think that he is trying to teach him a lesson, so erring is fine as long as he gives an honest effort.