Bad Player said:
So, just to be completely clear... the no-platforming/"censorship" is done by student unions, not the universities? How exactly does the process of getting a speaker work, and what role do the student unions and universities play in it?
That depends on the speaker and their role.
Sometimes, departments will invite an researcher from another university to guest lecture in the department. This is relatively easy to set up as it's a good opportunity for academics to publicize their research and it helps institutions and department to raise their profile. A lot of guest lecturers are contacted through informal peer networks (people working in a department tend to know other people in the same field) while others (particularly when guest lecturing in a foreign country) have a very definite speaking circuits where they will sign up ahead of time to do a bunch of guest lectures at different universities. Others, especially very senior academics, will be asked to give a lecture as the keynote of a conference or workshop they are attending at an institution.
There have been examples of guest lectures being protested (which is in and of itself not a problem as the right to protest is considered a key part of free expression) but they are solicited by the department or institution which invites them and ultimately, students have no power there.
However, most people who come to speak at universities are not academics who have been invited to speak there, they are invited by the student union. As well as representing the interests of the student body in negotiations with university administration (often very poorly, in my experience) student unions are also meant to serve as social hubs for students (especially undergraduates). Student unions receive funding from the university administration, which they will use to run facilities and events. Students themselves can also apply for funds from the student union in order to run their own social activities, like the rugby team in the article which will probably have recieved some money to pay for training facilities. Basically, the goal is to make students' experience of campus life more socially rich, which has nothing to do with the academic side of things at all.
Now. The key thing is that the student union is a private organization "owned" by the student body as a whole. It may have a few full time employees, but most roles within it will be filled by students elected democratically from the student body. Issues on which the student union takes action are voted on by the student body at regular UGMs. The university administration has absolutely no say in this, deliberately so because again the serious function of a union is to represent the student body in disputes with administration. The NUS, the umbrella organization to which student unions in the UK belong, works on similarly democratic principles.
This means that if, and let me give a real life example, a university Islamic society wants to invite a preacher with known extremist views to speak at union facilities using union funds, they can apply to do that, but the rest of the student body is perfectly entitled to use the democratic functions of the union to say "no, we don't want this person here". The no platform policy is something the NUS as a whole voted to have, and could at any time vote to repeal. Furthermore, any given student union can, without repercussions, choose to disregard the no platform policy (and there are examples of unions doing so). It is a relatively informal idea based on the principle that universities, as places of education populated primarily by young and fairly impressionable people, should not be used to spread or incite certain forms of discriminatory speech or action.
Now, the students who organized the talk or invited the speaker are members of the union, they have an invitation to the private club, so to speak. They have the right to initiate or cast a vote at a UGM. Whether they exercised it or not, they had a chance to express their views and to seek the support of the student body for their position. But the student union is under no obligation to abide by a set of ideological principles, such as some absolute form of "free speech", which its members didn't actually vote for. That's how democracy works.