The Kilrathi are not the dumb ones. It is the Terrans who are dumb to be caught. They would do anything to save their worthless lives, even betraying their own species.
There are surely more humans working for the Kilrathi, as there are Kilrathi working for the humans. And I cannot think of any serious malfunction of Kilrathi weapon systems, so the Terrans must be too dumb to sabotage. <g>