I’m agnostic as to the operational and legal merits of putting drug dealers who work for, or pay protection money to, the Taliban on the military target list. Of course a lot depends on how accurate the intelligence is.
What I’m sure of is that targeting them, whether for military action or ordinary drug law enforcement, makes more sense than simply ramping up Afghan drug enforcement generically. Drug dealing helps fund the insurgency (and warlordism). But that doesn’t mean that cracking down on drug dealing would tend to shut off those funds. The result might well be the reverse: raising prices, and therefore revenues. The trick is to concentrate enforcement on the people who contribute to the security problem as well as the drug problem, rather than on their competitors.