Well, guys... I published this shader to show that it can be used to achieve some illegal advantage. I've never used this shader in the game. I created and tested it just before publishing. As you know I make (modify, convert, repair, adapt etc) maps sometimes. So, I have 3 sets of Q3 (minimum):
1. to work on maps - with all necessary stuff
2. to test new maps - a pure set + some pk3 files to test
3. to play - a pure set + some custom maps played on servers

So, this shader is in the 2nd set. I ask everybody not to use in sets to play. Sharing this shader is a sign for admins to take some measures.

EDIT (a bit later):
One have asked me what measures admins can take if "pure" doesn't affect such files. So, there are 3 ways:
1. to remove such maps from servers
2. not to do anything, but to admit that someone can use modified shaders.
3. to invent something else

Moreover, I think, if an admin wants to have a fair play on his (her) server, he (she) should know and prevent ways and opportunities (like such maps) of unfair play.
Another simple enough and well known (I think) example of unfair play is to substitute "black sky" textures by visible ones. It seems to be demanded on space maps under rail-only configs (with BFG flights).
I think there are other ways to cheat... I don't want to use them, but to understand and prevent them. First of all, while making my maps.