Why would they arbitrarily pick a group of people travelling together and bump them ahead of time?
What if they get no shows/cancellations between now and then?
Why wouldn't they ask for volunteers at the airport if they were still overbooked at that point?
Will be very interesting to see if your friends report any empty seats on the flight. And even then, that's not a great indicator since they could have cleared non-revs/other standbys that OP should have priority over.
Seems like they are trying to get out of IDB/VDB compensation by bumping them off the flight prior to departure date.