What choice has the judge got?
Hibbert has been presented to the world as an official victim of the incident. If the judge allows proper exploration of evidence which undermines claims of Hibbert's presence at the incident; and his subsequent testimony, what do you think is going to happen next?
No right minded person is going to entertain Halls ridiculous theories. Made up theories of a crank is not evidence.
Hall insists all the coffins at the funerals were empty, allowing him to defend himself with such lunacy would pave the way for letting him exhume the graves of the victims only for him to then say the skeletons are planted.
Moreover if you read the judgement, CCTV footage shows Hibbert at the concert able and walking before the explosion.