Plenty of guys carry them like this, because the clip draw usually holds the gun in a way where the user's belt is covering the trigger guard. I seriously doubt anything can protrude through one's belt to grab the trigger.
Reholstering (or reclipping, I guess?) would be fairly difficult during a situation, but other than that there is no reason a Glock can not be safely carried between a belt and a body with a clip draw.
[/Support of my favorite pistol after Glock Haters run the thread into the ground
]