Giving a lecture about religious beliefs is very different to a religious occasion.
These aren't lectures, in the sense of the thing that university lecturers do for a living, and continually referring to them as though they are is doing the nutters' work for them.
The reason why nutters like renting rooms in universities (or getting hold of rooms via the booking privileges of people known to the organisers) is part of the spurious air of respectability. The SWP's "Marxism" festival takes place at the ULU and the adjacent IoE not because they're part of the university, but because it's a cheap place to rent some rooms and looks all intellectual and shit. If your reading group wanted to up its intellectual heft you could rent a room there too.
So if you rent a room in a community centre and get a semi-literate nutter in to shout loudly about killing de batty man, you look a bit nutty and people tend to back away from you in the street when you hand out pamphlets and even Andy Slaughter MP won't return your phone calls. But get a room at the IoE and hold a "lecture" on the problems of same-sex marriage in a multi-faith society, and you look like you're a moral philosopher.
The sort of events at which segregation is taking place are ranty speeches by lunatics with a taste for killing the kuffr, homosexuals, women who don't know their place, westerners, etc. A certain sort of student gets quite excited by all this sort of stuff, in the same way that a generation ago violent armed insurrection on behalf of the coming revolution was popular as a spectator sport for students as well. And enthusiastically adopting gender segregated seating is just as much a ritual, a shibboleth, a way of proving member of the in-group, as selling Socialist Worker on rainswept street corners is, and you don't get soaking wet either.
These aren't "lectures". These are gigs by colourful extremists who students follow in order to get a rise out of the oldies. Both the nutters and the audience would like people to think they're lectures with high intellectual standards, but in reality the whole thing is like middle class kids buying a leather jacket and painting "CrAss" on the back, or at least until they get a job as an accountant.
Seriously. Stop taking these people seriously. It's punk rock, without the tunes and the musical expertise.