She's been cleared for release by the people best placed to assess whether she should be cleared for release. If we are going say that somebody should stay in prison because they are reviled among the general public, why bother having a parole board in the first place?
I agree with that, but the necessary caveat is to consider whether releasing an individual accords with ordinary good sense and decency. If it doesn't then public confidence will be adversely affected. You may say that determining what is and isn't good sense is subjective. It is, but that doesn't mean we can't discuss what it is and come to a broad agreement on what is sensible and what isn't.
I will offer an example, to illustrate the point.
From what I can gather, experts wanted to release Myra Hindley and would have had a mind to. She was considered low risk (I'm sure that's true, too) and the Parole Board of the time wanted to move her to an establishment where she would be prepared for resettlement. I'm quite glad this was blocked by both the courts and politicians (including a personal intervention by Margaret Thatcher, who apparently blocked a decision of one of her ministers that could have led to her eventual release). I'm glad because, although she was low risk, she had never been fully candid about her offending and her release would have been an affront to all good sense and decency. As an aside, it would also have been a deep insult to the memory and dignity of her victims and their families (though, strictly speaking, that is a more minor consideration, but still important).
In the Hindley case, the criminological, medical and penological experts were wrong - totally and utterly wrong. Their view was plainly an affront to good sense and decency. The laymen politicians (as well as the courts) were right.
The reality is that professional 'experts' do sometimes have blind spots. This is because they are experts. It seems paradoxical to say it, but expertise can sometimes be a disadvantage in the exercise of good sense because it narrows one's focus and wider considerations are forgotten. This is why experts will make decisions that seem ridiculous or run contrary to good sense, even though what they are doing may be technically or legally correct. This problem cannot be cured. It is just the way of the world. The purpose of intervention by the government minister is to moderate this inherent defect in the system to ensure and maintain public confidence.