Some of the important SELinux settings (Booleans) moved from system-config-securitylevel to system-config-selinx. Therefor system-config-selinx needs to be installed by default. Ohterwise SELinux will be a very frustrating experience for the user.
policycoreutils-gui should be in the same comps file as system-config-services, I would guess.
To clarify: it should be installed by default in the same cases as system-config-services.
comps.xml change checked in
Fix confirmed with 20070123.nightly: <packagereq type="default">policycoreutils-gui</packagereq>
Confirmed with 20070124.1.