Either it could mean it is not a requir mentioned to be able to send broadcast packets to the machine. Windows uses broadcast packets for lots of things, like discovering UPnP devices, media centers, other machines file/printer shares, etc.

Or it could mean no need to have the ability to send the machine IP packets directly, so one can attack even if the machine is behind NAT.

There are far fewer ways to attack a machine behind NAT with no user interaction, but things like sending back false NTP or DNS responses, spoofing windowsupdate servers, or some of the peer to peer services built into windows sound like possible ways.