I don't think you need any sort of big conspiracy or consciously laid out political agenda. It's entirely possible (and, given the film, quite likely) that at least some of the filmmakers had a negative view of the EPA, and Walter Peck is a reflection of that.
Maybe, but if so Ramis was never particularly VOCAL about his anti-government views. He did, however, have a tendency to write stories with a 'slobs vs snobs' style, which pitted closed-minded, straightlaced people against laid-back relaxed fun-lovers who annoyed the authorities.
In a movie about college (that was a party fraternity against school administrators. In a movie about a country club, it's an old-money judge against a nouveau-riche goofball and his reliant-on-scholarships caddy. And in a movie about a start-up business, there's two natural options - It's gonna be either a government regulator, or a more established corporation. Only, well, Aykroyd's idea (Ghosthunting = Pest Control) doesn't work as well with an established rival ghostbusting corporation, because then you need to pull the world even farther from ours. So the natural second choice is to have the 'snob' be a government agent.
It's POSSIBLE that Ramis had a negative view of the EPA. I don't know. But the information we have from his filmography gives us plenty of reason to believe that he could well have made an EPA regulator a villain even if he DIDN'T have a negative view of the EPA. It's possible, if he did have a negative view of the EPA, that the reason was that he believed that there should be no federal environmental agency (it's also possible, after all, to believe that there should be an EPA but that the one we have is badly run, or that there should be an environmental protection plan but that the way the EPA is set up isn't particularly helpful.) The thing is, we don't have enough information based on his work to really tell. I'm not going to argue that we can't use text to determine an author's views, but we should tread carefully when things aren't exactly cut and dry. I think it's fair to say it's possible, but I don't think it's really fair to base any judgement of the people on it.
But again, all that is a secondary consideration. As I've repeatedly argued, even if Walter Peck was what the scriptwriter thought the EPA was like, that would in no way make him RIGHT.
So, to summarize my arguments here.
1) It's possible that the filmmakers didn't like the EPA, but we can't know.
2) It's possible that if the filmmakers didn't like the EPA, it was because they were laissez-faire conservatives, but we can't know.
3) The filmmaker's opinions on the EPA do not effect whether or not Walter Peck was right.
