Judging by the tone of your story, your friend was a union employee. Having worked for several years in a management office for the discipline of all union employees under our contract, and having attended countless arbitration meetings, I can positively assure you of two things.
1. Women get preferential treatment during litigation proceedings concerning unions, due in large part to the effect that most Unions have a male and a female representative for their members, and the women is without question always the sharper on the paperwork side. 4
Which leads me to...
2. Arbitrators always go with the paperwork. They are not like normal judges. They look at all the paperwork put forward by both parties, and rule off that. If your friend had a clear and well viewed habit of perceived sexual harassment or negative behavior,
And rest assured, the FIRST thing management does in these cases is stop the office, cold. Then they spend a day or week, depending on the size, getting written statements from EVERY worker in that office, going back 365 days, or the "statute of limitations for discipline". If the witness statements show any behavior like what is being "grieved", they prepare the case for discipline. They also review the persons involved for past discipline, prior offenses, and previous issues. They then review the notes and evaluations of the manager or supervisory chain. They then, and only then, when discipline has been decided upon as a path, speak to the accused, with a union rep present. The person is interviewed, or "interrogated" as the manual writes it, to discern their story.
Then all information is accumulated and discipline is decided as yes or no. They then, based off previous similar cases and past history, estimate type and scope of discipline. This all is compiled in a disciplinary report, which, if the person decides to fight the discipline, is given to an arbitrator, in triplicate. The arbitrator then goes over the ENTIRE process again, which usually takes 4-6 months, unless fast tracked (NEVER HAPPENS, Arbs are paid by the hour) and the Arbitrator hands down a decision, and in that decision he or she says two things. Discipline is the correct path, or incorrect, and the proposed punishment is fair. If it is unfair, they can alter the scope, but not the type.
tl:dr - Sounds alot like 1. Your friend had a history of this type of behavior, well documented and well established, and 2. he made a REALLY shitty case for himself to management.