Actually, both of those articles claim the UK court ruled that the journalistic activities David Miranda was indirectly involved with "equate" to terrorism. “I’m of course not happy that a court has formally said that I was a legitimate terrorism suspect..." quotes one of those two articles.
The UK court did not rule that way if you read the judgment. In fact, it explicitly states it did not make such a distinction. The court ruled that the law in question doesn't say that the government can detain people it suspects of being terrorists, it actually says the government can detain people who have any connection with such activity to determine if they are or are not involved. The court explicitly ruled that the law was not constructed to detain people who provide "probable cause" in the criminal sense, because the detainment is not specifically targeted at criminals or even suspected criminals directly. Its designed to provide the government with a tool to investigate people who might be, and for whom there doesn't necessarily exist criminally sufficient probable cause for search.
The UK court also ruled that while the statute refers to "terrorist activity" it actually explicitly defines the term for the purposes of the law, irrespective of what people consider "terrorist activity" to be, and the court was required to follow that definition. For the purposes of that statute only, "terrorist activity" is any activity that:
“(1) In this Act ‘terrorism’ means the use or threat of action
where—
(a) the action falls within subsection (2),
(b) the use or threat is designed to influence the
government or an international governmental
organisation or to intimidate the public or a section of
the public, and
(c) the use or threat is made for the purpose of
advancing a political, religious, racial or ideological
cause.
(2) Action falls within this subsection if it—
(a) involves serious violence against a person,
(b) involves serious damage to property,
(c) endangers a person’s life, other than that of the
person committing the action,
(d) creates a serious risk to the health or safety of the
public or a section of the public, or
(e) is designed seriously to interfere with or seriously
to disrupt an electronic system.”
Basically, its any act or threat of an act intended to influence a government or governments, involves serious property damage or mortal danger of some specific serious nature, and is intended to advance a political agenda. Notice the law doesn't specifically say you have to threaten to kill someone or kill someone. It actually says you have to act or threaten to act in such a way that death or damage is a consequence of that act. The court itself noted that the law appears extremely broad in its definition, but it wasn't being asked to rule on whether the law was overbroad.
The court ultimately ruled that the government had a legitimate reason to believe that David Miranda was involved with people who were at the time acting or threatening to act in a manner which was designed to influence a government and forward a political agenda, and those acts had the potential to cause death or serious property damage. All those appear true on their face, and thus the law states the detainment was legal. The law doesn't say David Miranda is a terrorist or was involved with terrorists, nor did the court so rule.
Its worth actually reading the judgment, because the court doesn't just rule on the merits of the case, it also summarizes the legal points made in the case both for and against. And if the ruling accurately summarizes the legal points being made by David Miranda's legal team, he's going to keep losing appeals, and he *should* keep losing. The argument being made appears to be this:
1. Governments should never interfere with journalists, ever.
2. Journalists must be allowed to decide for themselves on what they are justified to report.
3. If Governments want something from journalists, they should ask and the journalists should be trusted to respond to those requests appropriately.
The court went so far as to note that when the government witness explained their rationale for how those disclosures could directly threaten lives and damage national security, Miranda's team barely even responded at all, essentially saying "not" but without refuting any of those claims, as if they had no obligation to prove those assertions were unreasonable.
No matter how paranoid you are about government activity and how protective you might be about journalistic endeavors, that can't possibly be a winning argument anywhere. A better legal strategy would probably be to attempt to overturn the actual law itself as being unconstitutionally overbroad (I'm not as versed on UK Constitutional law, so I don't know on what basis you'd do that), but I have a suspicion Miranda's legal team isn't actually attempting to win this case on legal merit. Its attempting to use the case to try to make a non-legal point. The fact that they're framing the ruling as "see, the government thinks journalists are terrorists" when there's no way to read the ruling in that way tells me they almost want to keep losing, because losing makes their point and winning makes the story go away.