Um, it's not false advertising. This definitely happens. When they ran the same special last year, I (and a lot of other forumites here) successfully bought those R2 tickets.
They don't make such a massive loss because they have a fixed number of "R2 seats" reserved on each airplane alongside all their paying clients. Those seats may have been empty anyway, and you have to basically pay to have luggage or any other value-add (that would result in extra costs).
Filtered over all their destinations and all their flights over a few months, I reckon it's still a worthwhile promotion. It's effective too, lol, as their website crash demonstrates.