Trivia: The name of the town in the film is "Grover's Bend." This is a bit of a reference to the town of "Grover's Mill," which was the town where the aliens supposedly first landed in Orson Welles' infamous "War of the Worlds" broadcast.
Trivia: One of the Krites is biting the head off an "E.T." doll. Dee Wallace coincidentally co-starred in both "Critters" and "E.T." as the mother of each film's respective young protagonist.
Answer: Charlie had become a chronic drunk and the town considered him a crackpot with his claims about alien abductions being foretold through his dental work. Even though it was an accident, he could have been declared incompetent and a danger to himself and others; he possibly could have been involuntarily committed. Brad is protecting him.
raywest