I don't think the appeal was frivolous at all. The original appeal might have had little chance of succeeding, but Leeds clearly didn't just go in and say 'its not fair, reduce the ban' - they put together a case with some evidence of from other games. They then appealed the description of the original appeal as frivolous and the consequent additional game ban.
If the panel is going to apply this sort of thing it should be very clear and upfront, as it is in the NRL - 2 games if you plead guilty, 3 games if you fight and lose the case. No adding extra games on post appeal. That makes crystal clear to everyone where they stand. At the moment the disciplinary puts some of that out but then has this additional right to extend bans. Its utter kangaroo court territory.
Note here I'm not saying the original ban was too short. I am saying that clubs should be allowed to put in defences and not have them rejected as 'frivolous' if they genuinely believe there is a case and provide evidence to back that up. A perfectly reasonable outcome from the original appeal would have been that the ban was upheld despite whatever evidence Leeds produced. Or, if the system was as in the NRL at least Leeds and Newman would have known in advance that fighting the charge could lead to an extra game. They may well not have done so if that was the case.