I don't think the author is saying the clicks are malicious, just that they are lower 'quality'. Based on the authors experience he seems to be saying the intent of some facebook clickers is different than regular web link/banner clickers. He seems to imply the Facebook clickers have some other incentive to click other than to see the advertises website; and that incentive might be to collect 'likes'. And that actually makes sense to me, reminds me a bit of the incentivized clicks of the eagerly 00s, not worthless just worth a whole lot less than organic clicks. If Facebook has a lot of these clickers their inventory value becomes worth less.