Why wasn't Jason Stryker affected by Cerebro?

In X-2: X-Men United, Xavier is being controlled by Jason's illusions and made to try to kill all the mutants. However, Jason is not affected by Xavier's attack. Being a mutant, shouldn't he have been since Charles carried out a global attack on the mutants? Is it because he was inside Cerebro with Charles? Does this also explain why Charles isn't affected by his own attack?