S/C/D is not used to 'remove' AI traffic it simply toggles if PF3 should detect/interact with it.
PF3 has no control over AI traffic, other than to keep it out of your way whilst taxiing, taking off or landing. With earlier versions of FS there were utilities that you could use to restrict AI traffic using a particular gate by editing the BGL files. I'm not sure if such tools are available for MSFS or even if it's at all possible. FSUIPC does offer a ZAP facility that will remove AI traffic in front of you when you hot an assigned hotkey. Again I'm not sure if that works with MSFS, but certainly worth investigating