There was a chap called porcorosso or something similar who used to post a lot on pprune. I remember him describing some of the crm issues of having the owner sit in the other seat.
Attempting a night vfr approach in a Citation X into an 1100m field in near cat 2 conditions would suggest questionable judgement.
However from articles in Flying magazine and elsewhere I know these heavy iron biz jets can sometimes be equipped with head up and even synthetic vision. I got the impression that this was a way around the fact that quite a lot of biz jets are not autoland capable.
One hypothesis I am sure the Bfu will investigate is whether slant range played a role. It is perfectly possible to be visual at a thousand feet looking through the mist from above. As you get lower you are looking through more of it and lose visual reference with the runway. This is is obviously not good at night with no ils etc.
If you had all the kit and knew how to use it maybe this kind of approach would not sound so crazy. But the end result is pretty indicative.