yes Roleof is right.
The regulator will protect a spectrum reciever because it is upstream in the reciever but the servos use +-power in pass through on the board and only the signal comes from the reciever. Don't use a regulator and you will smoke servo's. Been there done that! You will cook them on straight 2 cell lipo without a regulator maybe not immediatly but within a month it will happen.
I cooked 3 KO's this way and it was on a road trip race. A weekend trip across the U.S. became a total bust