There is no such thing as a public authority exemption.
We literally have amendments (5th and 14th) that state government(s) cannot:
“deprive of life, liberty or property without due process of law.”
Droning certainly is depriving someone of life.
AND
it is done without due process.
Statutes cannot override rights and immunities.
If it’s okay to murder American citizens by drone, why wouldn’t it be okay to murder American citizens in other ways? Droning is just a method.
No way should any of that be permitted by the Constitution.