Trivia: Michael Myers kills Deb by pinning her to the wall with his knife the same way he killed Bob in the original 1978 film.
Trivia: An alternate ending was written where, in the final moments of the movie, the scene would suddenly cut to the Silver Shamrock Factory from "Halloween III: Season of the Witch." You'd see the witch, pumpkin and skeleton masks being produced... then suddenly, you'd see dozens of Michael Myers masks on an assembly-line, implying some sort-of connection between Michael and Silver Shamrock. This ending was ultimately thrown out because it was deemed to be too weird and fan-servicey.
Trivia: In a multi-layered homage, the movie that Corey and Jeremy are watching is 1982's "The Thing" which is a remake of "The Thing From Another World", which is the movie that Laurie and Tommy are watching in the original "Halloween." Oh, and of course, "The Thing" was also directed by John Carpenter.
Trivia: The font in the opening credits is the exact same font (right down to the blue color) used in the opening credits from "Halloween III: Season of the Witch," which famously didn't feature the Michael Myers character and told an original story. Fairly appropriate, because (MINOR SPOILERS) Michael Myers plays a somewhat smaller role in much of this film, which primarily focuses on a new character who is driven mad and almost becomes a "New Michael/Boogeyman."
Answer: The implication seems to be that there is some sort of subliminal connection between the two that they both pick up on. I personally took it as Michael somehow subconsciously feeling the "evil" brewing within Corey... almost as though he sees his own evil in Corey. Thus, he lets him go and subsequently "teams up" with him later on. They're a twisted form of kindred spirits.
TedStixon