But of course not good sir, all pyskers draw their powers from the warp after all. And that connection allows chaos to enter the materium more freely thereby inducing mutations.
The pyskers themselves are in constant danger of succumbing to madness or summoning daemons or mutating whenever they channel the powers of the warp into their psychic abilities.
How prone they are to the perils of the warp lies within each pyskers strength of will and mental fortitude.
The Emperor being the strongest pysker in all of Humanity he is quite easily able to block out all harm from the warp using his immense will power and pyschic abilities.