If this was just a guy posting trash on Facebook I'd probably side with you. If you read the details of the case, you will find that this is not just someone ranting. This appears to be someone conspiring to commit rape, murder, and kidnapping.
I did read the details of the case and I have to disagree. He's not ranting, he's fantasizing, but there's no evidence that he ever planned to go further.
Whether the primary web site has a disclaimer or not, does not change the fact that this goes beyond the simple act of writing about a sick fantasy. He offered to kidnap someone for 5,000.00. He went and found a recipe for chloroform, then built a pulley system to string up one of the people he was talking about kidnapping and murdering.
He offered to kidnap someone, he never did kidnap them, nor did he or anyone else complain when these plans didn't happen. He said he built a pulley in the emails but he didn't actually build it, nor did he make any chloroform. Surely if you're making a criminal conspiracy involving chloroform, a human sized oven, and a pulley system then actually obtain chloroform, a human sized oven, and a pulley system.
He used a Police database illegally for the purpose of gathering personal information about the people he appeared to be conspiring against (it was more than 1). This goes well beyond simply discussing "unconventional thoughts".
Lets change the scenario a bit. If I was to claim I want to kill someone on Facebook, I'd be a person of interest but not doing anything illegal. When I go out and search for recipes for poisons, I'm still not illegal but I should be under watch, especially if the poison is generic household items which I may have on hand. Once I start illegally gathering personal information about the targets I claimed I want to kill, would I not be conspiring to commit murder? What if I owned a gun, would that be enough? (Remember that this person was a Cop and had a Gun, as well as a position of authority to abuse, and could have been legally stalking victims without anyone's knowledge on "patrols")
Ok, here's another scenario.
You really hate John and claim you want to kill him on FB. You look around for information on poisons because you're curious, or you're fantasizing about how you could kill him. And because the guy really pisses you off you become mildly obsessed and gather information using a work database (even though doing so for this purpose is unauthorized and illegal).
Yet under no scenario could you actually imagine yourself doing so much as punching John.
If you believe it's reasonable, would you want the guy as a neighbor? Invite them over over for dinner? If so, good for you. I'd prefer to see a person like this under watch and psychological monitoring at a minimum.
I wouldn't, not because he's a criminal, but just because he'd creep the hell out of me.
This is a guy who might commit a serious crime in the future, perhaps even wants to. But he has never done so, nor has he specifically planned to do so. All of his previous plans were merely elaborate fantasies that he never took a concrete step towards implementing.
Personally I'd recommend a mandatory psychological evaluation. IF that suggested he could take the step towards moving those crimes into reality then I might consider watch and mandatory counselling. Otherwise he's innocent of everything except the misuse of the database.