Yes that sounds right, the power is not regulated by the CC3D before being passed on. The BEC on the ESC normally puts out 5vdc regulated. The CC3D takes that and regulates it down to the 3.3 volts it needs. It passes it unchanged to it's other ports so the receiver is getting the 5vdc regulated by the ESC. Other than the USB connector all the other CC3D power pins are just connected together.