Obviously this person 'lost it', but does that make them insane? A moment of madness, did they just loose their temper or are they indeed 'mad'? That is why I put the question. There are degrees of insanity and therefore responsibility.
I was not one of those calling for draconian punishment or suggesting the punishment should be to 'cage' or lock the individual up. If they are indeed found to be sane (or rather not insane) and therefore should be punished the option to restrict their liberty can take a variety of forms besides imprisoning them. Plus the fact of having to pay significant compensation could also be considered a major part of the punishment.
Part of any punishment must also be to make any victim (in this case the company, the staff and passengers affected) feel they have rececived justice for their ordeal - no?