Umpire Interference - Dropped 3rd strike

[Linknblue]

Taken from Facebook group…..Situation: USA Fast Pitch Softball, 2 outs, runner on first. Catcher short hops a swinging strike 3 call. Batter becomes batter/runner and is heading for first. Catcher attempts throw to 2nd base to retire what she thought was a runner stealing. Umpire interferes with her throw and ball sails into left field. Both runners are now at 1st and 2nd. What’s the mechanic and correct call?

My call would have been: Call umpire interference, dead ball and runner returns to 1st base. Batter is out. My logic: Because catcher was trying to put out a runner advancing the interference stands even though the runner was forced to the next base. The batter cannot run on dropped 3rd strike because I called interference and immediate dead ball. I put the runner back just as if it was a called 3rd strike w/out the dropped issue. Correct logic or would I have screwed this call up?

Researching book, nothing I’ve found “directly” addresses this issue. Examples given are runner attempting to steal and she intended to steal but wasn’t because she was forced as soon as dropped 3rd strike situation occurred.