I'm not sure on the technical ruling details, but it looks like something like that:
They did not care about the data, officially. As they have already recording, sms, ...
They just wanted to access the home of his phone that his restricted by the passcode.
And he explicitly refused.
Nothing say that once they would accessed, they would have been allowed to access private data or being able to use any of that in the trial.
It is like a 2 steps process. First they should be granted access, then there is the question of incriminating data that could encrypted or not.
It looks dubious, but it is how it is presented to be able to get such a ruling.
As an equivalent, imagine that cops ask you to unlock the steal bar reinforced door of your entrance because they have a warrant and you refuse. And you claim that their might be naked pictures of you inside of your home this is why you refuse.