If you make it the managers call you will have how many people watch monitors to give him the nob to challenge something. If you make it on field call the players will just be looking for a signal off someone. The Aussies/Steve Smith got caught doing the same thing in cricket.
15 seconds to challenge? I think your objection depends on the management team seeing the replay from the best angle in 15 seconds, being sufficiently convinced to act, getting word to the manager, and getting word to the 4th official in that time.
However, if just get rid is your preference, I won't object to that either.