Doesn't sound like a loophole to me- sounds like fraud.
A loophole would be something like- "you don't need a license if you have a tv for educational purposes", and you tell them you watch the news.
Your idea sounds like a bit of a scumbags cheat, they should be able to set up a device over the road from you which blocks any signal going to your house, it's blatant fraud. Like telling the police they aren't allowed on your land to arrest you after you have just committed a crime!
The police AREN'T allowed on your property unless they believe and have evidence you are guilty of an offence!! even the police need a court issued warrant unless they believe or have evidence that you are committing a crime on the premises.
who's to say its fraud? you are allowed to use your TV to watch pre recorded programs and DVD's and catch up TV services such as 4OD, Iplayer etc etc. you must be seen to be using the device to watch live as broadcast TV. I'd be happy for a van to sit outside my house and TRY to block my signal seeing as that is unlawful aggravated harassment and its perfectly legal to watch all +1 channels as they are not live broadcast.