The full sentence in the whitepaper is: "These constraints were supposed to protect hash from GPU and ASIC implementation, but a GPU miner appeared on the scene in 2 weeks after this technology got public attention." Thus, contextually we know that his meaning in the word "protect" is "ensure they do not exist". He considers the very existence of a GPU miner a failure of the algorithm, when, in fact, a GPU miner can and should exist as long as it the performance gap is closed. Currently GPU miners are 2-3x as performant / efficient as CPU miners, and by dga's calculations they shan't exceed ~5x the performance / efficiency. Thus the algorithm has completely succeeded at what it purports to do, and has met its primary goal.