That's not why anything was done over it. If they had kept it to political opposition they'd still be using it today. It's specifically using it to root out spies that the US dislikes.
But that would be a scope shift, so if we're going there, now do Stingrays, PRISM, paralell construction, and FISA - but I won't say these are quality arguments. Outside this admitted whataboutism on my part, the very narrow defense I'm indicating for NSO in this specific case is it was within the sovereign right of this customer to use it, and it's only going to happen more often as this market is infinite.
I still think the Americans are just mad they got owned by Uganda. I'd bet this isn't the first time they have scored points against the low expectations of their "advisors," either so: well played. Point Uganda. I think this is a really funny precedent, and I can't believe I'm defending either of them, but the arguments back just aren't powerful when compared to demand for the tools of sovereignty, and we should give the conseqeunces of that due consideration.