Interference: Who's Out?

[Timmy]

I've been hanging around this board for a while and it looks like there is a lot of great feedback from a lot of experienced officials. I'm a longtime SP player who does some umping in rec leagues on the side and plan on doing more of it once my playing days are over. I recently witnessed the following situation in a tournament and was wondering what everyone thought.

SP, ASA rules
R1 on 1st, 1 out. Batter singles to right field, R1 attempts to take 3rd. Throw to 3rd is late, F5 throws back to 2nd late as BR slides in safely stretching the hit. R1 takes off for home and as F4 steps toward home to throw (any kind of a throw home and R1 should be dead) BR very obviously reaches out his leg while he is still in contact with 2nd and trips F4. BU immediately calls dead ball and calls BR out for interference and calls R1 out because of the interference. Common sense seems to tell me that the BR is out for committing the interference and R1 should be out because the defense wasn't allowed to make a play on him, however, I'm having trouble applying the rule book to this case. The book seems to describe a case where both runners would be out when a runner commits interference to prevent a double play, however, there was no double play in this case since BR was already safe and was still in contact with 2nd base at the time the interference was committed.

I'd appreciate any input anyone has.

Thanks,
Timmy