Where do I get the official (not authoritative opinion) interpretation?

If you own a copy of Baseball Rule Differences, the BRD, you already have the definitive answer. From Section 296, 2008 edition:

Following the [coach's] interference the assisted runner is out, but the ball remains alive.

Play 4: Bases loaded, 0 out: B1 flies to right. The coach pulls R3 back to the bag. The ball is dropped. R3 scores, R2 scores, slow-footed R1 tried for third but is thrown out as B2 takes second. Ruling: Take the result of the play except R3 is out.

The staff of PBUC was adamant. The OBR umpire should ignore the penalty for 7.09i (delayed) dead ball [or 2.00 Interference (immediate) dead ball]. When I pressed the spokesman, Mike Felt replied succinctly: "Ball is alive and in play correct."

Try this play:

Continued...