Re: how long ago was this?
It may be the lack of caffeine here but I couldn't see any indication of when this stuff happened.
The gentleman may have been trying to communicate with Microsoft for months, perhaps years, and after getting shoved from pillar to post has decided to recourse to this action.
I would imagine that at far as he is concerned he started off with a working computer and then an update broke it. That, in his mind, puts the fault firmly and squarely at Microsoft's door.
Furthermore, the massive tag on the law suit isn't to get $600m but to make Microsoft sit up, take notice and give him what he bought in the first place: a functioning version of Windows 7.