I don't know why politicians are getting involved in this.
It was long ago established - quite rightly - that in the UK politicians have no right to get involved in individual judicial decisions. They set the framework but individual matters are dealt with by an independent judiciary.
Parliament has decided that prisoners serving certain custodial sentences have recourse to the Parole Board to seek release. They have also determined that the Parole Board is not allowed, by law, to publish the reasons for its decisions. I disagree with both those principles but whilst they are as they are politicians should concentrate on lobbying for a change in the existing arrangements rather than trying to interfere in a case where they (or more probably their constituents) feel a wrong decision has been made.