Jury nullification.
Hopefully, but only after the shooter has spent thousands of dollars on lawyer's fees.
If I were charged with shooting the drone I would sue the drone's owner for invading my privacy. In any event, I don't believe a jury would find the shooter guilty of a crime since they would know that some other drone's owner could fly his drone over their property with impunity based on a conviction of the property owner in this case.
On another much more serious note, my son is a pilot for a major airline and he knows of at least one flight crew that has been virtually blinded by a laser during a critical landing procedure. That crime is far more dangerous than anything a drone could possibly do, and the perp is almost impossible to find. Maybe after a few hundred passengers are killed as a result of some teenager's fun and games played with a laser the feds will get serious about stopping that criminal activity and prosecuting the offenders to the full extent of the law.