Re:This isn`t about 'testing' the GPL... (Score 1)

Since they have lost the right to do so, then the GPL they granted to the software is itself invalid IN THIS CASE ONLY due to the authors not holding the intelectual rights (according to the courts) in the first place...

The settlement with Mattel ostensibly transferred rights from the authors to Mattel. This would appear to be an acknowledgment by Mattel that, prior to the settlement, the authors did have rights to their software. I'm no lawyer, but I doubt you can transfer or assign something you don't have. Based on what others have posted, it seems that if the authors did have rights at the time they licensed the software to others, then the earlier licenses stand.