I am a UK resident and don't fully understand the Class-Action system.
However, this is a very well documented, internally acknowledged problem with these displays. It is fixable and is caused by a bad solder joint at the point the backlight cables attached to the LED trays. It is not a failure of the panel itself, as with the 2006 17" iMac panels (vertical lines), or the discolouring of the early 27" iMac panels.
Under warranty or AppleCare, the process is quite specific. Display issues like this result in a new panel AND backlight board.
When Apple have internal documents that explicitly refer to a particular procedure, rather than just the general procedures with Service Manuals, it seems to me that they are well aware of it being a problem.
I won't bore you all with the long list of specific Macs and their known problems. However, Apple have again and again stated that they will not build crappy products or play to the bottom end of the market.
As this guys notes, Apple products are marketed as being significantly better conceived, designed and constructed than the competition. These statements need to be backed up by an experience that matches.
The UK Consumer Laws would definitely help this guy. Such an expensive repair to an expensive product, that is expected to last longer than 18 months, is not acceptable. There is ample evidence to back up his claims that the problem is widespread and that Apple are aware of it.
Springing for an OOW repair for a customer who has invested in one of their expensive products should be a matter of course. It certainly retains the customer and is the kind of thing that helps convince others to invest in a Mac.
Good luck to him, I hope he wins.
For those of you who feel he has no complaint, put yourself in his shoes. Apple should back up their claims with a fitting warranty period. Show faith in their technology with a worldwide 3-year warranty.