I honestly don't think it was a "move" as such. The legal matters adjournment tells me that this was not planned. The prosecution would have to ask the judge whether they could be brought into court, given this is the defence phase and they are prosecution witnesses. The judge has to decide if any late evidence is admissable after hearing submissions from both sides.
So this also tells me that Nick and Joe have only just surfaced. Being (ex)friends of IS, I imagine they've been following the trial and have been thinking hang on a minute this idiot is describing us. Maybe even worrying that he is actually blaming them. So they've contacted the police over the weekend.
The police would likely only be able to brief the CPS this morning. There will have been a bit of craziness behind the scenes I bet. Prosecution counsel will have asked the judge for the adjournment at the point that he was first able to do so. So all of this has happened in a rush this morning.
I've only seen this sort of madness a couple of times when I was court reporting. It's really thrilling when it happens though.