Did this run score?I said yes.(m)

[dsimp8]

Situation:

One out.Bases Loaded.Infield Fly Rule in Effect.Men's SP.

The Batter pops up to 3B.I call infield fly rule.(out 2).The 3B drops the ball(not on purpose,just a bad league). The runner from 3rd sprints home and the runner at second slowfoots it to 3rd.(I guess he doesn't know the rule). The 3B goes and tags 3rd which means nothing since the runners are advancing at their own risk. The SS alertly tells the 3B to tag the runner going to third which he does. I say "Out on the tag" and that the run counted since he made it home before the tag was made. The opposing coach comes out to question the call and I explained to him that since it was not a force play that the run counted even though it was the third out. He still did not understand son I explained to him that if a runner at 3rd scored before a batter-runner got thrown out at 2nd trying to stretch a single to a double,the run would count since the BR had to be tagged out. Was I correct on my call and was that a good way to explain it further? Where is this in the ASA rule book so I can share it at our meeting this weekend? I've looked and looked but cannot find it. I was worried about it a little but since it was a blowout, I had no hard feelings about allowing the run.