[officialtony]

In first reading 8-4-2k, I would have agreed that R3 was out on the interference call. However in rereading 8-4-2k, I now understand that there are two separate condiditons that may exist in this rule.

" Any runner is out when he is contacted by a fair batted ball before it touches an infielder . . . . "
Here, the pitcher is considered an infielder and thus when it touched the pitcher it took the option of interference on R3 away.

" . . . . or, after it passes any infielder, except the pitcher, and the umpire is convinced that another infielder has a play. "

Since it has not passed any infielder ( the pitcher is excluded in this ruling ), this part of the rule does not apply.
Therefore, I agree that R3 gets a no call for interference. That he was tagged out because he stopped is unfortunate, but a good no-call overall.
Would have been nice to have all this time to make the determination at the time of the incident. Sounds like you both did a nice job.
Well Done!