Umpire INT, Rule Clarification?

[chuckfan1]

Had this recently, and Im sure I got it right, but in looking in the college book, the penalty doesnt seem to be completely laid out. At least what Im reading.
Sitch.. Catcher, after receiving pitch, comes up throwing , trying to pick off R1. F2 , in his throwing motion, makes contact with me, on my chest protector. Throws goes into right field. R1 makes it to third.
I come out.."Time, we got umpire INT, runner, back to first".
Looking in my College book, I find the rule, but it doesnt seem to go far enough. Rule 6-3a mentions the PU interfering with the "catcher's attempt to throw anywhere".. and runners return. I dont see anything about "if the throw retires the runner". Its mentioned on Batters INT, but not Umpires INT....am I missing something in there?

It was a "relaxed" summer league, Connie Mack game, and Paul Abbott, coaching 3rd, ex major leaguer, comes down...
We have a short talk..he gives the old standby.."I played in the bigs for a long time, and I never saw that."..
I told him what happened, the throw didnt retire the runner, runner goes back. Paul asked about "arnt umpires part of the field"..etc..
I even mentioned how it just recently happened in the Majors, though I couldnt recall the particulars.
And Paul says.."so you mean the major league umpire just said.."my bad".."
We both laughed a little, and I said.."well, maybe not those exact words, but yeah, probably pretty close to that".
Paul is an asst at a local JC here, and the head coach was in the dugout. A pitch goes by to the next batter, then he comes out. Wanting to question the play, get help etc. Was said in a calm manner, but I told him, weve moved on, its too late at this point, and see me between innings, and Ill answer any questions.
Of course he didnt. Im sure if it was a regular season game, wouldve been different.
But does anyone have anything? Shouldnt the book clarify that?