@Geri

They still have the opportunity to appeal. In these situations it is fairly common to defer enforcement of a ruling until the losing party has had the opportunity to appeal, to avoid a ping-pong effect (you lost, you must do X, you win the appeal, you just undo X).

Often, there are more consequences if you lose the appeal but kept doing the thing ruled unlawful in the first case. This is why the Met Police are collecting evidence but not making arrests. If the government wins the appeal, the organisation has always been proscribed and the police and make arrests and launch prosecutions based on the collected evidence. If the government loses the appeal then the proscription has been unlawful since the first case (causality is exciting in the legal system) and any arrests made after it may be grounds for cases for wrongful arrest or unlawful detention.

It’s very Schrödinger’s cat: the current legality is established when the appeal collapses the waveform.