... all the more reason for a "fruit of the poisoned vine" doctrine to be adopted in the UK. The whole stop should have been thrown out in the US if it were based on an unwarrented bug. Not that it will be, nor that "poisoned vine" is safe in the US.
I'm not certain that applies here.
His detention was long after the Guardian had broken the story. There were many news stories about many British organizations before that took place. It is quite reasonable that Greenwald's home was bugged because it was well known he had a large collection of documents. It is quite clear they have both audio and video feeds at his home and his office if you read the documents the court released.
It wouldn't surprise me if any number of agencies had already raided his home, copied his disk drives, and otherwise done their espionage job at the same time they were planting their bugs around the place, and he likely has people watching CCTV taking note of everybody who approaches his home. There is nothing "poison vine" about that; considering the background they are lawful (even though they are blaming the messenger for the message).
On this ruling, the court said that if Schedule 7 applies at all, it applies completely, therefore the full time can be taken.
What they didn't rule on was the fact that while on the surface it was a stop for national security reasons (likely with recordings in the home showing him loading up the classified documents and discussing how to carry them through security) they didn't touch the concern that the motives were to bully and harass, rather than protect state secrets. As a parallel, an officer may be able to legally bring me to the station for questioning every morning before I enter the office, but it would take a while before we could make a case for harassment. Similarly, this single instance fills the letter of the law, and while it strongly appears it was designed by a legal team to threaten and harass to the full extent permitted under the law, there is no proof it actually crossed the line.
Considering how much the previously-released stories had offended so many people in government, it is quite likely, nearly certain, and very probable it was an attempt to threaten, but these guys are all legal experts. They know exactly the extent of the law, exactly what to write, exactly what NOT to write, and exactly how far they can push. The conspiracy is clear to everyone at every level, including the judges. The problem is the level physical proof that is required. Considering the legal experts who launched the attack and their reasoning, you can be pretty certain that such evidence does not physically exist.
Even if one of them came out and said "Put me in jail for breaking the law. We intentionally railroaded the guy, studied exactly the limits of harassment before it broke the law", everything about it immediately becomes hearsay without physical evidence and is dismissed.