Selecting LSB Group w/ Gnome Default (gdm)

During install when you select Gnome Desktop Environment and then select "Detailed Selection" and pick the LSB group it has a conflict that LSB requires "default" (i.e. KDE Desktop Environment) instead of default-Gnome. Is this a bug?? Shouldn't it require either "default" or "default-Gnome"?? Is there a specific reason people who choose Gnome can't have LSB?