I just looked this up and see that the article is written on 6th Oct and the even happened on 6th Oct.
I do not understand how it is that someone in an electric wheelchair is only finding out that there isn't access on the day of the event.
It might be the Edibrugh UNion (the debate society) organising but that doesn't mean that, being based at a University, the issue wouldn't have been solveable as there would have to be accessible venues of equivalent sizes on the campus. The only issue that would prevent this being solved would have been enough time and/or someone not thinking to check.
I see it is the lift that is the issue, and might have been organised by eg a society who might have less experience than eg if it was going through processes that involved staff who were used to organising events and checking these things but I'm surprised given the profile of it that someone more senior didn't step in to 'help' and avoid this sort of problem.
Surely it isn't ideal either if there is a lift somewhere that can't take the chair and hopefully it is noted down - although I don't know if it is the weight (which seems unlikely) or the size/shape and so there isn't any kind of sign because people who don't have to manouvre similar chairs just hadn't noticed and/or assumed that it wasn't an issue because before getting in there the person with the wheelchair could see they wouldn't fit.
It just goes to show though what those with disabilities actually contend with, if an event where they are an invited speaker at a big university has these issues spotted at the last minute then it gives insight into what it must be like everywhere else/navigating daily life?