Is it? The FSF's description of the judgement is that the training was fair use, but that the actual downloading of the material may have been a copyright infringement. What software does the FSF hold copyright to that can't be downloaded freely? Under what circumstances would the FSF be in a position to influence the nature of a settlement if they weren't harmed?
Is harm necessary to show in a copyright infringement case?
Copyright infringement causes harm, so if there's no harm there's no infringement. You can freely duplicate GFDLed material, so downloading it isn't an infringement. If training a model on that downloaded material is fair use then there's no infringement.