So why is it still there?
Probably three reasons :
Mexican authorities are corrupt, and can be bought cheaply
ISIS is better armed than Mexican Federales.
Mexico wants to export ISIS for idealogical political reasons to control the Southern border and keep it open.
The fact that BOrder Agents have seceed the first thirty miles of the border to Mexico says volumes.
In a sane world they would watch it for a while to gather intel than bomb it while the terrorists are at said camp.