I have to disagree, I don't think it tells us anything at all. At the moment, he's the head coach so he's going to be at the event. The alternative, if they've already decided he's going, is to omit him from the panel thus giving the game away that he's going to be sacked. They set this up weeks ago including the attendees from the club so RE turning up is to be expected and not an indication either way.
As above, what else are they supposed to do? Omit him and reveal (possibly to RE himself) that he's getting sacked? I just don't see it myself.
Basically, I think having this panel has backed them into a position where all they can say publicly is that he's supported and that he'll be the coach going into next season. I suppose they would look silly but an RE-no-show would tell us much more than him turning up.
EDIT: also, looking silly (or downright ****ing stupid) hasn't stopped them from making decisions before!