Here's why:
* Anthony Fremont's Power: Anthony, the young boy who holds the power of his thoughts becoming reality, has decided that Pete Van Horn is his "best friend."
* Mr. Bevis's Fear: Bevis realizes that Anthony's "best friends" don't last very long. Anthony has a history of making those he dislikes disappear, and he doesn't hesitate to use his powers against those who annoy him.
* Bevis's Attempt to Please Anthony: Bevis becomes extremely submissive to Anthony and treats him with extreme deference, trying to avoid upsetting him in any way. He even offers Pete a "business proposition" (which is actually a bribe to stay away from Anthony).
The mob doesn't turn on Pete; they are simply terrified of him because of his connection to the powerful, dangerous, and unpredictable Anthony. The episode highlights the dangers of blind obedience and the unpredictable nature of power.