I'm not saying his concerns are invalid just because he posts them on slate. I'm not saying his concerns are invalid at all. I would be able to criticize the validity of his concerns if I were able to read them. I have no choice but to ignore them because I'm not prepared to pay the price of my personal data. And I find that quite ironic, since apparently they are about protecting online privacy in the first place.
I don’t see how that follows. Even if the author were positively malicious, why would you ignore their concerns about privacy, which affect you and everyone else? It’s a non-sequitur.