Vlasak was outlining his NLC system as he was planning on implementing it in his TC.
What part of this do you not understand? Did you read the complete thread on Vlasaks idea posted above?
NLC according to Vlasak's idea would mean changing the weapons you want to use NLC and then adding specific scripting to characters who would be attacked by NLC weapons. This is easily done for a TC as everything in the TC is being made by the creators. They can create all creatures with the correct scripts and still they would have to decide what that creature does after it wakes up from being unconcious.
Yes you could add Vlasak's idea straight into BG2 but you would only get benefits if you specifically designed a quest around NLC. Otherwise you would have to rewrite every quest/creature script in BG2 to account for an attack using NLC!
Rewriting the entire game is exactly what he was talking about, that is what a TC is: a Total Conversion of the game. Again read the link above to Vlasaks post and then actually read the post, the very first line of it says: "I've added this feature to our TC BG2 add-on CZ." Vlasak then goes on to point out: "I'm not going to apply this possibilities into BG1 or BG2 - it will be very complex and especially very time consuming to turn all the BG1/2 original content for Non-Lethal attack option. In case of whole new mods, their creators count with this possibility from the beginning and everything is simplier." Only the content of the mod would work using NLC.Vlasák is not suggesting anything close to "rewriting the entire game" An idea like Vlasák could work on a finished product like BG2, if pessimists like your being don't actively try to discourage it.
No it doesn't and yes it would, good luck with that.Suffice to say NLC doesn't exist at all as it is, and is a deserving and useful story telling tool to try to create.