Unique Play

[Marty Rogers]

This one came up tonight at my asso. meeting.
Actual play in HS game:
R2, R3, one out. Batter hits a very high fly
straight up between home plate and pitcher's
mound. It lands fair, and spins, rolling back
toward home plate. It keeps rolling, coach yells
to let it go (appears it may go foul). It is
slowing down just as it reaches the plate. R3
comes sliding into home plate, slides into the
ball, and it goes rolling several feet away.

I don't know if the ball was actually on the
plate, or just in front of it. I don't know
if this even matters. What do you think the call
is? I thought the runner is out for being in
contact with a batted ball, but don't know if
this is correct. Any ideas?