BB10 is QNX and the same QNX makes up OS1 and OS2. I'm sure at some point, OS2 will be "updated" to BB10 to keep the phones from fragmenting from tablets.
The article is a bit misrepresented but I think the author meant only the mobile part of the BB10 phones is going to be integrated into the PlayBook. The PB OS 2 is BB10 with mobile feature like phone and text messaging backed into the OS.