The palm strike is safe for the officer to use, but it's also quite effective. A palm strike done on a slightly upward angle has a tremendous amount of leverage. One need only to strike a heavy bag suspended from a stand or ceiling to see this. Compare the reactions of the bag when you punch or palm strike. There's a more violent jump in the bag when you palm strike.
Punches have a primary effect on the target struck.
A punch to the head will usually affect the area the knuckles made contact with. Palm strikes have a secondary effect. A palm strike to the head won't cause much damage to the contact point, but will have an effect on the neck and usually jars the body. A palm strike done under the chin will often produce a one shot knock-out due to the whip lash effect. A palm strike anywhere to the head area will almost always affect balance, because the strike will take the assailant's ears out of line with his hips.