I flew small airplanes for a number of years and I can tell you that it's extremely unlikely that a pilot would see your drone or the strobe under the circumstances you describe.
You say that you were able to see it only at 100+ yards away while...
It's on the drone pilot to yield to a manned aircraft.
CFR § 107.37 - Operation near aircraft; right-of-way rules.(link)
(a) Each small unmanned aircraft must yield the right of way to all aircraft, airborne vehicles, and launch and reentry...
Unless this pilot had super vision I dont think they could see your drone.
WHAT? A handfull of times?
I have been flying Drones for quite some time now and have NEVER had to take evasive action for a plane or helicopter. Planes flying at low...
Since you mentioned that this person is hostile and litigious, direct involvement with him sounds like a no-win situation, just let LEO handle it. Or get a local TV station involved. If this is happening on a regular basis, have a reporter see...