An open letter.
Dear Mr. Zimmerman
As far as I can tell from the documents, the informant volunteered a whole laundry list of unsubstantiated allegations to the detective, including the "OMG command prompts are spooky" one that the whole blogosphere is up in arms about. A few of these allegations were actually related to the emails which the detective was investigating, so he summarized the entire interview in his affidavit.
Then, when the whole thing went public, it was made to look as if the police was considering the use of dual-booting and command lines to be suspicious. I can see that the informant was ignorant, paranoid, and malicious – but what evidence do we have that the detective shared this ignorance? This seems to be based only on the fact that he included the informant's ignorant statement in the warrant application. But he explicitly introduced it as a statement from the informant:
[The informant] reported that Mr. Calixte used two different operating systems to hide his illegal activities. One is the regular B.C. operating system and the other is a black screen with a white font which he uses prompt commands on.
Now, I would assume that the detective follows the rule that when he applies for a warrant, he will disclose to the court everything the informant told him about the subject. I don't know whether such a rule is actually written down in Massachusetts, but even if not it sounds like a sensible one to follow.
Assuming that the detective follows such a rule, I can see nowhere in the warrant application where he, in his own voice, asserts or even implies that using Linux is suspicious.
You seem to prefer that the detective, on his own initiative, should have decided that the informant's remark about dual-booting into Linux were irrelevant to the case at hand, and therefore he should have omitted them from the warrant application. I think that is a very dangerous direction.
Surely we don't want police to hide exculpatory evidence in their possession from the court when they apply for warrants.
Do you really trust the police to distinguish correctly between "irrelevant information" and "exculpatory information" when they put together a warrant application?
I don't, and I would much rather see police leave in a few irrelevant statement from informers than neglect to mention facts that might contradict probable cause.
In fact, a good judge might take the entire laundry list of disparate allegations from the roommate as a sign that the roommate was grasping at straws for ways to get Calixte in trouble, thus reducing the roommate's credibility. If they had been left out, Calixte would really have had cause to complain.