It's for fighting bushfires so everything gets fired straight down. Obv it could be used for dumping other chemicals so I could imagine the CIA hitting rival cocaine plantations and possibly important food crops of nations they want to destabilise with a growth retardant of some sort.
Discussion
I think you're giving them too much credit
You believe the CIA aren't capable of such things?
I think they're capable of all that and much besides. You seem to be trying to come up with a rationale that is compatible with the interests of ordinary Americans (at least through the CIA lens) while I think their use of any tool is likely much more based on naked self-interest and a desire to retain power
You think ordinary Americans are interested in destabilising other nations and allowing the CIA to monopolise cocaine production and distribution?
Nope, but I think the CIA rationalizes that as providing funding for things that are ultimately good and patriotic. Few people are the villain in their own movie.
I suspect that most people are more preoccupied with presenting themselves as good rather than being good or convincing themselves that they are. It's all signalling.