Admitting that, as a helo bubba, I have little-to-no cred to weigh in here, but doing so anyway:
It seems to me that modern warfare has caused a schism between the definition and purpose/meaning of "ace." I think the underlying idea was that an ace survived 5× 1v1 air combat events or 1 or more many-v-many, etc. and killed 5 enemy fighters in the process. Five kills defines "ace" because kills are a measurable stat. Don't confuse the metric with the essential idea or goal (there's a great short book on this: The Tyrrany of Metrics).
I think "ace" is a complex idea encapsulating the inherent danger and odds of dying in air combat. "Ace" signifies the 2- or 3-sigma of fighter skills... someone with such a record it couldn't possibly be from luck alone.
If I successfully killed 5 subs with torpedoes, it would certainly be highly improbable and notable, but not because I survived -- most subs can't do anything about aircraft, so it's one-sided. It'd be like giving an artillery crew some form of "ace" for killing infantry units.
I'm in the drone kills don't count for Ace crowd.