The article is poorly titled, it is not much of a problem in National Parks or Park Service (Dept of Interior) lands because only a modest portion of those areas are forested. USFS (Dept of Ag) has a much worse problem because they have more land, much more forested land to provide canopy cover, fewer legit visitors and even fewer law enforcement.
Also that article only touched on the meth labs but in many ways those are more dangerous. Meth cookers are there boiling their product together most of the times whereas most pot plantations are usually unattended as they grow on their own. Plus a meth lab can even be hidden in a tent or a much smaller area and anyone breathing or using that shit is ****ing loony tunes and will try to stab you a zillion times if they don't pop you. Best to hope that you don't run into one of those wackos, although your chances are much better if you avoid CA and MO forests.
One other thing the article leaves out is that hte park service and to a lesser extent the USFS have had a lot of their manpower diverted for Homeland Security detail without any accompanying funding or personnel for the increased burden.
As far as the Kris Eggle murder down at Organ Pipe, that was drug related I believe but didn't have anything to do with drug production on US public lands. IIRC there were some guys who had just killed four people as part of a contract killing, drug related of course, in Mexico and then were fleeing from the Mexican police north through AZ when Eggle ran into them and they killed him.