Alister never planned to let his subordinates deal with powerful enemies. After all, the purpose of recruiting subordinates was just to deal with miscellaneous work.
If an existence far surpassed his power, then it was impossible for his subordinates to deal with them. And since he was cautious, he would never accept that his subordinate was the same power or stronger than him.
Knowing that Jake and Bruce couldn't deal with the upcoming monster from the dimensional gate, he nodded at their request and signaled for Jake and Bruce to stay far away.
Although he could protect Jake and Bruce since the upcoming monster was just a mere Monster Saint, Jake and Bruce would be reduced to burdens if they were caught up in his battle with the Transcendent Saint.
Jake and Bruce were well aware of Alister's intention. They didn't want to become a burden during the battle between Alister and the Monster Saint so they obediently listened to Alister and retreated.
Shout to one of my readers, I_Am_Death , for guessing the Eighth Monster Saint's identity!