They claim "By signing up—again, it costs nothing!—you can read the rest". If that's false, that not only a really shitty move but should be a crime - they're obtaining something of value (your e-mail address, no doubt to spam it with subscription ads) under false pretenses.

I just went and tried. Free signups unlock the article just fine. Gonna pat myself on the back for doing the incredibly minor legwork now :3