So after re-reading the article about PMC's working in old Mexico, I started to wonder. Since only Mexican Nationals are allowed to carry firearms, I wonder if dual citizenship would count?
Consider this; In the Washington post article they talk about how non-mexican security personnel would have to team up with armed locals to provide the "armed muscle" needed for actual ops, as well as for the security specialists own protection.
However, considering the Narcotrafficantes proven track record of co-opting corrupt military and police, would any PMC employee really trust their lives to some locals?
Whereas if dual citizenship would qualify them for government licensed security work, you might see a sudden upswing in applications for the needed paperwork.
Time will tell.