I've seen the hand over slide with thumb toward you cause problems-pinched palm, ejected round hitting heel of hand and falling back into port, and cut palm from rear sight edges. I use and promote the gripping from the rear with thumb and index finger on serrated area of slide mode of operation. You may lay the pistol over toward the weak hand during this operation as long as you control the muzzle direction. Main thing if doing the "push-pull" method is to make sure your trigger finger doesn't inadvertently engage the trigger.
This scenario actually happened during the CCW class I attended many years ago.