The multiplexer does not have any adjustments either physical or via software for the delay. The delay issue is the result of the Pioneer head unit being in the manual backup camera mode (Pioneers software not RVS). When the multiplexer sends the signal to the head unit to switch to camera mode the head unit switches immediately as it should. When the multiplexer drops the signal the head unit switches back to the radio mode then after a 3 second or so delay (not adjustable) back to the manual backup camera mode. This is what causes the behavior the OP asked about.
The display that Bob has has the the multiplexer intergrated to the display and has additional functionally as well as eliminates the interaction between the RVS multiplexer and the Pioneer head unit.
The cameras and multiplexer are RVS.
Probably more info then you needed!