1) Play as described above - B-R retired by Infield Fly - and runners advance due to ball rolling away. Is it:
A. Interference by retired player - R1 called out.
B. Dead ball by ?? and runners have to return.
C. Runners allowed to advance.
1) Anytime an offensive player interferes with a fielder attempting to field a batted ball the ball is immediately dead. Other runners return. (ASA 8-2-F EFFECT)
I don't see how you can combine 8-2F's EFFECT when interference by a retired offensive player (8-7P) was possible. 8-2F is for interference by a batter-runner and the player in your original post never really became a B-R because they were out by IFF at the same moment their turn at bat concluded.
Rules Supplement #33 Interference includes B-R's under it's discussion of runner interference. It says -
When a runner interferes with a fielder, the umpire must determine if the interference occurred before or after the runner who interfered was put out and then apply the appropriate rule.
I did think calling dead ball and keeping runners from advancing was the appropriate action (10-1?), but I found something in May 2013's Plays and Clarifications that could be applicable to calling interference by a retired offensive player in my scenario.
Runner Missing Home Plate:
Play: With R1 on 2B, B2 gets a base hit to RF. R1 scores but misses home plate. After entering the dugout, R1 returns to touch home plate and draws a throw.
On the throw to the plate, B2 advances to 2B.
Ruling: Once a player enters dead ball territory, they are not permitted to come out of the dugout to touch home plate.
When R1 did so and drew a throw, R1 was guilty of Interference by a retired runner. The ball is dead and B2 is ruled out. If the defense properly appeals that R1 missed home plate, R1 would also be ruled out.
Seems like B2 only advanced to 2B because of the opportunity created by the throw home and wasn't an available play at the time R1 left the dugout and drew the throw. If so, runner(s) advancing due to an opportunity created by a retired player knocking the ball away could result in a similar call. If no one tries to advance, it doesn't really matter whether the ball is dead or not (i.e. no harm, no foul).