hawker, don't be jumping to conclusions. It is not known (yet) if the pilot even ASKED if a slot in EDDF was available to him or not. And in an emergency he obviously can divert there or to Mannheim, Frankfurt-Hahn, or other fields. NO ONE forces a pilot to continue flying into a short (1166m) runway with 4 knots tail wind with a Citation x, on a foggy night, except the pilot himself.
So far it is assumed that it was a private, non-commercial flight. There were guests waiting for the plane at the terminal to board and continue on to Bratislava. I'm sure the pilot was not prepared for the situation he discovered when approaching EDFE, perhaps hasn't even performed a VFR approach in that type of aircraft for ages (if ever). But that's all speculation...let's wait for the accident investigation report.