Don't think this is a fair criticism of the club really.
When you are accused of what we are accused of, with all the potential consequences that would follow from a finding that the charges have been proven, you concentrate on defending yourself in that process. Of course you can and should state your belief that you are innocent (assuming you do believe this of course!).
But in terms of the PR battle, the starting point is that we have no realistic legal threat we can make against the "City are guilty" brigade. And they know that. Lots of people have said the club haven't done enough here, but I haven't seen a single realistic suggestion of things the club could have done that would actually have made a difference (I've seen suggestions of things the club could have done, but those things wouldn't have made a material difference to the coverage IMO). Say for example we tried to ban Carragher from the Etihad...that might feel great. But he can still comment on our games. And honestly that would only make things worse. It would just feed the "City are cheats" narrative.
All this is known to the club, who have legal and PR advice of the highest quality on tap. There are reasons that they have acted as they have.
The time for a PR offensive on this is after the result of the hearing, not before.