The order came after the earnings call. My bet is that those are largely replacement airframes to get rid of the old 700s since the Max is performing well for fuel numbers.
Also, in typical CEO newspeak, he said we are reducing capacity. What he didn't say is that we are just reducing our forecast growth by a couple of percentage points, not actually shrinking. The guy with his hand up the puppet's butt used to say that every time Wall Street would start getting edgy about overall industry capacity in order to calm people down. Then we would grow anyway.
In other words, it means nothing. Tell the investors what they want to hear and then do what you are going to do anyway. That's how these clowns operate.