What was he/she doing? No radio,

Maybe the guy works night shift and this was his afternoon. My SO and I
both worked 2nd shift and got home after midnight and had the grill lit
cooking steaks at 2am many nights. We also swam in the pool and
generally did stuff in the middle of the night that normal people did
in the afternoon. This included going for a ride in the plane. It's
really nice to have an uncontrolled field all to yourself. My SO likes
the landings the most so we would spend an hour or two just doing touch
and go's.
I wouldn't think the guy at 1am doing training strange, the guy with
the daytime job fueling his C-150 at 1am is strange.