OK, I’ve read the ET license and the sticky notes on copyright, but I still have a question:
Is it permissible to use textures/mapobject models from ET in a Q3A map, from a copyright POV? There are some nice ET grasses I’d quite like to include in my Q3A WIP.
If not I’ll make my own, but is this OK?
Technically no, although it’s unlikely that you’d incur the wrath of ID’s / Activision’s lawyers etc.
In other words, you can do it on your own conscience 
you can make a download disclaimer that everyone who wants to play this map has to own et and rtcw. otherwise they are not allowed to play the map because it uses rtcw assets with only can be used if someone bought the game.
but im no lawyer so its complete nonsense. 