Your theory that Pattis might hide the evidence like a knife is plausible. Keeping the knife (if it exists) from LE using extra- ethical methods does comport with my knowledge of Pattis. And since we are talking about the very public figure Pattis, plausible speculation is fair game IMO.
But I don't see how it would benefit Pattis to invent Fudge. Why put it out that a knife existed, unless it was also known by Oattis that LE knew about the knife. We still don't know what weapon(s) were used in the murder- there is no benefit to Fotis Dulos to name one. If the knife existed and were known, why put it out that anyone handled it, unless that was already known by LE?
A knife does seem plausible to me. It also seems plausible that Fotis Dulos intended to use a knife to threaten and aid in an abduction. If he had intended to kill her on scene, surely he'd have been a little better prepared with spatter control and cleanup materials- and perhaps materials that would kill leaving fewer bodily fluids around.
The murderer may have over estimated his knife's ability to obtain compliance.
Also, I think it is highly unlikely Fotis carried a gun to the scene because if he had, mentioning his gun ownership would not be prejudicial. It would be relevant to proving the case.
And he'd need some kind of plan to subdue JFD. Either he'd have to threaten her to comply or overpower her and restrain her using surprise to his advantage. I think he either messed up the surprise thing, such as by making noise in the garage, and switched to the bloody plan B, or didn't try it at all, thinking JFD would comply by knife point.
However it went down, offering the police any leads to a weapon would not benefit the defense that I can see.
MOO
Edited to add: it could be that Fotis Dulos and Pattis were aware that a knife was discarded in Hartford, and wanted to tease out a confirmation from LE that they recovered the knife (gulp) or did not (the whole knife thing was a silly rumor!)
That does make much more sense to me than just filling airwaves with incriminating rumors that otherwise only harm F. Dulos. They could have been trying to decide how to handle the knife evidence if, indeed, there was going to be knife evidence to explain.
I doubt very highly LE does not know who fudge is, as he was reportedly incarcerated for a short time. (You don't readily spring a John Doe. Or a Fudge.) The story, as told, does not include anything that Fudge would lie about. And I'm sure LE asked him about it.
What makes sense to me is Patti's may have been trying to find out what LE knew about the knife. It does not make sense to me that Fudge is a fabrication of Pattis'.
MOO