As explained in the previous message, the TCXO is automatically turned ON when the state requires it (Rx, Tx, etc.) - as long as you called the function SetDIO3AsTcxoCtrl before.
The enclosed screenshot is an example where the chip is in Rx duty cycle mode and shows how DIO3 and BUSY lines behave. You can see that each time the chip enters the Rx state (corresponding to BUSY line low), the TCXO has been previously turned ON thanks to DIO3. The delay is the one you defined in the call to SetDIO3AsTcxoCtrl.
So, as long as your RF switch does not draw too much current in active mode, you can use DIO3 to power and control it.
Click thumbnail to see full-size image