Wrong verbiage, point still stands. Probably a decent number of MAU on Facebook in that range but logging in and checking one thing twice a month is a big usage difference from daily or semi daily sessions that last for minutes, not seconds.
"Active" there means opened, not actively consumed. I'm "active" almost every day, but the majority of my sessions are below 20 seconds. They mean nothing to Facebook, and they mean nothing to me. Facebook lost the value it had for me.