This may well be old news but first time I noticed Reitman discussing it: Entertainment Weekly asked Ghostbusters director Ivan Reitman to react to a common (among conservatives and libertarians at least) reading of Ghostbusters as having an explicit and intentional anti-regulatory, pro-small-business message.
While I've been unable to find it online, it's on page 113 of EW's Sept. 19/26 double issue. They ask Reitman: "Did you ever imagine that National Review would name Ghostbusters one of the best conservative movies?"
He replies: "I never knew that. I've always been something of a conservative-slash-libertarian. The first movie deals with going into business for yourself, and it's anti-EPA—too much government regulation. It does have a very interesting point of view that really resonates."
Jesse Walker wrote about this point in February. Ben Schwartz at suck.com laid out the Baby Boomer conservatism underlying Harold Ramis' comedy, and also notes the Reagan-era perfection of Ghostbusters' anti-reg message.