I have been reflecting on this some more. I think the fact that so many men seem to think the outcome is fair is because if it was judged to, or rather upheld to be rape, those same men would quite probably have to examine their own consciences about how they had treated women in the past.
So 1 in 4 women have been raped - I am one of them - I believe this figure. This also means that statistically speaking men know a man in their social circle who has raped even if they are not aware of this, or he has done it himself. It is that simple. If even an absolutely clear case of non-consent is explained away, or acquittal is bought, it sort of salves the consciences of the substantial number of men who do not wish to recognise that their friends/fathers/sons must also have raped women, or worse, it helps them explain away their own acts. If it becomes harder for women to come forward, it is easier for men to believe what they do is 'okay'.
That is the first thing. The second is that if men agree out loud that this case was not rape, and condone various humiliating practices shaming the victim (chanting??) then it maintains the more general control and power men have socially to commit such acts, because they are not (potentially) rapists or rape apologists, they are simply enacting a communally accepted view and judgement. So, again, it is the safer option if men want to retain privilege based on sexual dominance. Which many, many do. It becomes a bit of laddish bonding, boys will be boys and all that.
Let's not forget that the police also know that DV spikes after football matches, and these kind of cultural enactings have real consequences for women. Chanting her name should be prosecuted as a hate crime as it is one.