Why would you think that?
They didn't learn from anything else that the 'few idiots' that seem to follow you have done over the last 35 years - like dropping concrete slabs on the heads of local waiters for instance - why should this particular example of sub-human behaviour be any different?
here for instance is a report that references a United team bus being attacked in 1986, with Ammonia being sprayed into people's faces.
https://www.independent.co.uk/sport...l-bitter-rivals-share-a-respect-a6921956.html
Did you learn from that? Doesn't look like it from where we are sitting.
Here's another report from 2006 that records the time when your 'few idiots' attacked an ambulance taking a United player to hospital.
https://www.theguardian.com/football/2006/feb/23/newsstory.sport1
That 'few idiots' that follow you around really do get around don't they? Its almost as if there's actually a sizeable element of your support that consists of subhuman scum and the rest of you just minimise it every time it rears its very ugly head.
So what basis do you have for even hoping that lessons have been learned? Have there been any arrests? Have there been widespread repeats of the public requests for people who were there to supply the police with footage recorded on mobile phones? Because from what we can see there has been a pretty big attempt to sweep the whole thing under the carpet and pretend it didn't happen.
Which is pretty much par for the course for your club, isn't it?