What is the Call -- Runner Returned to First Base on Steal?

 
At a Hagerstown Suns game...
 
With no outs, the batter (B1) has a 3-2 count, and the runner on first base (R1) is stealing on the pitch. On the pitch, B1 is called out on strike-3. The catcher's throw to second base is late and R1 is called safe at second base. After the field umpire calls R1 safe, the plate umpire calls "time" and motions R1 to return to first base.
 
The umpires and coaches huddle and, indeed, R1 is returned to first base. No one in the stadium understands the call. Can you help them?
 
Call
There could be several common scenarios on the play below (batter interference, catcher interference, batter hit by the pitch while swinging, balk, etc., etc.). However, none of these results in both a delayed dead ball AND then the stealing runner returned to his original base (since he was not retired on the throw). On this play, as the catcher threw to second base, the catcher's arm struck the umpire and it interfered with the throw. This is a delayed dead ball (NF 5-1-2c). Since R1 was not retired by the throw, R1 is returned to first base.