Is Kelkoo still going? I would have thought they would have gone bust by now. Maybe they have investors essentially funding this lawsuit in the hopes of a payoff.
Google shopping won out because it was free for merchants so everyone reasonably priced was on it and attempted to force merchants to include VAT and disclose shipping so it actually gave consumers meaningful results. Kelkoo and the like were useless, half the prices jumped up once VAT and shipping were included and the coverage was far from complete.
You still see some of these useless comparison sites listing themselves into Google shopping, but I think most people are like me and hit back as soon as they realise it isn't a real merchant. Generally I only end up seeing them when I am looking for something hard to find, and I have already been to the merchant they are pumping direct from google shopping and seen they don't have stock, but the useless comparison site hasn't caught up to that.
My guess is Google's tracking means they can see that these useless comparison sites aren't the search results people are looking for, so they drop them down the order, which is what Kelkoo can't admit to themselves so they imagine Google are deliberately dropping them down the order. Hopefully once this case is resolved they will go bust and disappear.