Oops I forgot something very important, don't try what I mentioned with two synthesized receivers, one of them has to be a OLD FASHIONED varicap tuned unit, perhaps even both I did this trick many years ago, to listen to sideband.
I would guess he has heard that doing that kind of thing would cause major interference to station, I have never heard that one, so I am not an expert.
I see at least one problem about trying this, as I understand it, if you wanted to block the neighbors FM receiver one of the first things would be knowing what station the neighbor was listening to,
I could see the possibility of generating a strong enough signal with the combination of the IF and the receiver frequency allowing the user to hear a different signal altogether if one was present at the time, but I don't think it would create a problem with another receiver there fore the FCC wouldn't care.
I used to listen to a radio station on AM620 with a reel to reel tape recorder (just a tape recorder no radio combo unit), but you had to have the microphone stretched all the way out and horizontal. It worked great until the teacher caught me and told me to go back to study hall, cuz I was supposed to be practicing my trumpet, not listening to the radio.