The reason there is a negotiation is the same as the reason the club suspended Sam for breaking team rules, not for the alleged incident: to come out and say that Sam did this, without conclusive evidence or Sam's admission, leaves the AFL, in the first instance, and the club in the second, open to defamation. Neither are a court, their findings are not privileged. If I were advising Sam on this (and I am clearly not as I am typing this out here instead), i would tell Sam that he has the upper hand in this negotiation.
As an aside, I would put money on one of the QC's opinions to the club being on this point (most likely in framing the initial suspension).