"Out of interest, why?"
Probably, Nigel, for the same reason that many professional pilots find it odd too. I'm sure you know (or should know!) that flying below MSA IMC is only OK under radar or on a procedural cleared route where that level or above is acceptable. To then 'divert' off that route at FL90 without a **** clue where the hard stuff is is OK with you?
AF certainly know how to screw things up! Who are you with?