Gi over, the old grey suits couldn't run a bath never mind guaranteeing the safety of anyone... He should be able to attend on a different day at very best...
I've been to several hearings, including those resulting from me being threatened, and have never feared for my safety. Referees should be kept in separate rooms to the clubs and players, they will enter the hearing room before them and leave well before the hearing ends.
Attending on a different day, that'll work. Under FA discipline regulations the accued players / clubs have a right to ask questions of the match officials but only through the commission chair, that is going to be tricky if he isn't there. This isn't crown court where cases run over 6 months ... !