With all due respect to the late Mr. Gomez, that doesn't make much sense. Any difference in length of time is negligible, given human reaction times (see John Boyd's "OODA loop"), ie the amount of time you will take realizing you need to defend your gun from a grab and actually do so, vs the hundredths of second difference between a leather holster, or kydex holster, won't make the difference.
What you need is a holster where your gun only comes out with a strong, very deliberate, pull of the gun. If you want the holster itself to protect from a deliberate grab, leather v. kydex is not the answer, you will need real active retention devices. Meaning going beyond the typical "open top" concealment holster, whether kydex or leather.