Has he tried contacting one of those "Accident at work not your fault" legal weasels?
Ordered to commit jockstrappery (particularly Kevball) on a floor known to be wet - and thus a known identified hazard - followed by incompetent medical treatment.
Yes, he should certainly take the MoD to the cleaners. This is precisely the sort of entirely avoidable accident which H&S@W was supposed to have put an end to.