I don't quite understand what all the fuss is about from the direction of the Daily Mail - it seems to me that the Judge (who unlike journalists sees the evidence, hears the argument and knows the law or can two opposing experts (barristers) explain the law to him without the need to bring it down to a non technical level) exercised his discretion and did so correctly.
The jury are charged with finding the facts of murder - the facts of murder are 2 fold: that the accused committed 1) an unlawful homicide against the victim and 2) did so with an intent to kill or cause serious bodily harm. They don't have to find motive or reason, just homicide and intent. That is the jury's job, nothing else. The unlawful homicide was admitted so the sole question for the jury was 'did Tabak form an intent to kill or cause serious bodily harm to Jo Years?'
Given that the jury don't have to find a motive or a reason in their deliberations it becomes a question of 'does the watching of violent porn assist in the jury finding an intent to kill or commit GBH or is this evidence that might through the jury off track and thus prejudice the accused from the fact to be decided?' In certain factual scenarios it might assist the jury and remain unprejudicial but I can't see that it does here. Tabak admitted to the killing - he just said he had no intent - the jury found that he did have intent because of his actions - his conviction was fair, there was no bad character evidence to get in the way of the jury concentrating on the fact they had to decide - the fact it was a majority call shows it was a tough one - and Tabak wasn't prejudiced by having his non crime related dirty laundry shown in public. The fact the Daily Mail seems to want trials to be based on moral judgement tells us more about it and its readers than the functioning of the judicial system which here, at least, worked.