Hi there Douth
This is a Arma 3 Creator DLC, which means that the assets are not a part of Amra 3, If any of these assets were added to the Altis server, every player would need to own the DLC or have the compatibility mod at all times to be able to play on the server.
We try and keep the server as new player friendly as possible, which mean not having required mods or DLC to be able to play.
So, while it may have a lot of good assets, it would fall under the same category as a mod and would need to follow the same rules as mods, including not being able to use the Assets in this CDLC.