As you say, they'll always counter with that argument. Perhaps one way to head that off, for those unfortunate enough to be assisting an investigation, would be to refer to the monitoring procedures that the companies presumably have (my non-airline employer does anyway) for counting sick days and having 'offer to help' (meaning 'we're watching you') meetings for those who have more sick days than average.
I'm not sure that was the story in this case though - the way I read the story was that he was being a good guy and wanting to get the pax to their destination. It's not like there'll be another one along in a minute from Aberdeen to the Faroes.