Is it possible (and if so how do I do) to inhibit the Broadcast Messages sent by the shutdown command to all terminals with user processes attached to them?

As I understand it, shutdown(8) in SysVInit reads from /var/run/utmp via getutent(3) to find out which terminals has user processes associated with them, and then it sends Broadcast Messages to those terminals...

We have a machine-machine interface to a HA SLES machine and getting unexpected Broadcast Messages complicates things a lot.