I fly for a major european national carrier and have jumseated a lot all over Europe: Germany, Portugal, Spain, Italy... In my airline it's the commanders decision to accept cockpit jumps. A lot of my colleagues try to avoid layovers in the UK, because everything is so complicated from security to the antique airports such as the prehistoric guiding system at Manchester ( but this is got nothing to do with Pablo)... Anyway to summ up, I hope he wins the case and if the commander for example wants to take his brother in the flight deck then so be it.
There you go, lets bring back common sense to UK airports.