It's really out of order. It's also really weird how the press are able to do things like this, when you consider with some other trials nobody is allowed to even mention the defendants on social media in case it would cause a mistrial (Rapey footballers, grooming gangs etc.). How does that work?
Because he's not been charged and isn't on trial.
There are pro's and cons either way. It's an open and transparent light on the judicial system with allowing the press to report X person has been arrested for Y, else you can get to the point people are arrested, taken away and no-one is allowed to know.
The reporting restrictions would come in when the person is charged and on trial, to be lifted after it's finished.