I don't know if I understand you correctly but if you are saying that the handheld tactical nuke launcher isn't available in the demo, it is. You just need to spawn it in the Sandbox Editor as of now.
You can also easily spawn all the nuke weapons and tanks in the Editor. In-fact, the demo has two types of the handheld tactical nuke launchers, one comes with two rounds of tac nukes that you can just fire anywhere and at anytime. The other seems to be the same except that it requires a lock-on target.
(This was a response to Frisker_Q)
[Edited by Knightmare2k8, 10/28/2007 3:41:16 AM]
Yeah i know it's there, what i was trying to say is that you can't get it in the game without using the editor.
That's because the commands are locked and can, apparently, only be invoked at mapload, and i think the issue is that you don't start directly in the map, but there is a in-game intro movie for it first, which might be why you won't get it in-game.