It seems like it probably was. Since none of their defences were allowed, then the jury had to simply decide factually whether the acts occurred. "We didn't do that" is one type of defense, so it stands to reason they didn't offer that defence and the acts themselves weren't disputed in the case.

This article says specifically that:

[The court] has ruled that mass loss of life from climate breakdown and the government’s failure to act on the science are irrelevant to the circumstances of an action, for the purposes of the defence of consent to damage to property. That is – protesters deeply-held and factual beliefs are no defence.

So the defendants weren't saying they didn't do it, and why would they? It was a demonstration, and claiming it never happened would defeat the purpose.

So that means that as a simple matter of law it's open and shut. They admit they did it, and they don't have any legally allowed defense for their actions. However, the jury are judges of fact, and the only way they can find them not guilty is if they determine that actually no they didn't do it.

That flies in the face of the cases presented to them, so it has to be jury nullification. I assume there was someone in the jury who knew about that loophole and informed their peers.

I don't see any mainstream outlets reporting on this - shocker I know. The neoliberal hegemon isn't going to want people talking about this, because they avoid jury nullification by just not talking about it and implying in court that the jury has to follow the law. If this news starts to spread and people start talking about it, it's going to get harder and harder to find juries that don't know about nullification and then these acts are going to get very hard to prosecute in a way that is seen to be legitimate.