From what FreakyLike and I have noticed, it is based on the sourcemod not being compatible with CS:GO specifically, as the basetriggers does not work correctly. An example from
notifyMOTD explains that a workaround (
here) was needed to give users the ability to be shown the webpage by using javascript to popup the page.
Edit:
Seems as though it is based on CS:GO and not on Sourcemod.
Topics similar to this:
http://forums.alliedmods.net/showthread.php?t=193408 &
http://forums.alliedmods.net/showthread.php?t=189892