Incidentally, conspiracy is an affirmative defense. You have to produce the relevant evidence you were framed for it to work. In fact, all defenses, with very few exceptions are affirmative, if the defendant opens the door suggesting an explanation, he/she is admitting they did it. That's why a good and competent defense attorney always points out holes in the prosecutions case because they're whittling away at the prosecutors burden of proof, the "Beyond a reasonable doubt".
So far as I know, it isn't a named or enumerated affirmative defense, but it sort of acts like one in that it would only make sense in the context of prosecution evidence that, if believed, would make one guilty. One defense would be to present an alternative interpretation of the evidence (reasonable enough to create reasonable doubt), that the evidence was manufactured or otherwise made to look bad by the supposed conspiracy.
Len hasn't got anywhere near that theory, instead just caterwauling about meanies on the Internet and claiming they're various people involved in the case, based on no evidence at all. None of this would create a reasonable doubt as to his guilt when compared to photographs and witnesses testifying that he did, in fact, trespass, and was by his own admission notified about the fact that he was forbidden from entering the property, in writing, before he did it. After all, the notification is part of the "conspiracy" he complains about.
To the extent it is a defense, it would be excludable, because nothing Len has said is even remotely relevant to whether or not he trespassed or did the other things he's accused of doing. (Which is more or less in agreement with what you said.)
Also, so far as we know, Len does not have competent counsel, or any counsel at all. Despite the docket having been updated the day of the waived arraignment, there is no indication that any counsel appeared, and the only document was filed by Len himself, which he wouldn't be doing if he had counsel present.
