Firewall Configuration and Broadcast/Multicast

I have made some testing for the firewall and the 2 configuration methods using the “Stealth Ports Wizard”.
My computer belongs to a Network and i am running WinXP 32bit with CIS 3.5.57173.439. The network is NOT configured as trusted.
When configuration is set to “Alert me to Incoming connections stealth my ports on a per-case basis” CIS is Allowing BROADCAST and MULTICAST packets and when configuration is set to “Block All Incoming connections stealth my ports to everyone” CIS is Blocking BROADCAST and MULTICAST packets. I have used Peerguardian2 to check if CIS is blocking Broadcast/Multicast packets or not.

Is it a bug or it is supposed to work this way?