It's a while since I flew this one but there were several "standard" routes, and one of them used to be via Faya Largeau-Kisangani so a diversion to Cairo may not be that unreasonable. Bear in mind this problem may have started in the early hours of the morning and there may
have been a distinct lack of both medical faciities and open and/or useable airports on this route until you get a long way South. I understand
they were airborne for around 5 1/2 hours prior to landing at Cairo, so just a very rough guess but that puts them at around maybe 20N or 15 N before turning back...
In BA's case a medical diversion is usually only made after a lot of discussion via satphone with both the medical professionals and the Company Control Centre.