I'm just waiting for someone to pipe up and say Northern's social media policy is a breach of some consumer law or human rights.....
As someone who has worked alongside my employer's social media team for a public sector body that is even less popular than Northern, I can only say that the job is nothing short of a nightmare. Generally speaking social media feeds are used to publish information & to answer general queries. They are not forums like this for people to continually express their outrage at whatever the day's outrage is, nor is it a medium to spread malcontent because someone has an axe to grind. But this is exactly what I see with monotonous regularity. Often a thread starts out as "Why is the xx:xx to Victoria late", then when the Twitter team respond with something like "Sorry but there is a crew shortage" it can then often descend into "Blummin' Typical" & "Northern are a disgrace" & "I hate Northern" none of which helps to inform or resolve.
And there are the predicable regulars who pop up time & again with exactly the same rants, the same insults & abuse. I've seen this in my work, on Northen's feeds & indeed right across the net. Contrary to what some members think here, simply muting or ignoring some posters isn't an option. When you run any kind of social media group, especially something like Twitter where single posts can go from a few views to trending, you have to keep an eye on every post to ensure that things aren't getting out of hand. The media does monitor trending feeds with a view to a quick story, so some rumour or incorrect piece of information can quickly get out of control and before you know it the story is all over online & printed media.
My employer's feed has a very similar policy to Northern, keep on abusing, threatening or disrupting threads and out you go. No 'ifs', no 'but's just off you go. And I suspect the same will be true across many company and departmental feeds. The other option would be if things got too difficult to manage to simply to pull the feeds altogether, as Whetherspoons have recently done. Its not really a major deal with a public house chain, but if TOCs pulled theirs a valuable resource would be lost because some people are simply addicted to messing things up for others.