Most adult males have well conditioned reflexes to protect from blows to the groin. Habit from years of painful blows from objects, and assholes.
So, is it a good offensive tactic to deliberately attack a reflexively protected, non lethal site that leaves the upper body of the attacker defenseless, and necessarily within arms reach of the opponent? No, it is not good offensive tactics. A feint to the crotch might be useful. What if he has little tiny balls? Or what if he is wearing a cup? If he is wearing one, he must have heard about you from someone, He knows you are a pretend tough guy.
People who are fighting for any non-lethal reason are easy meat to anyone with a military outlook toward physical conflict. Bridge of the nose, nose, throat, sternum, solar plexus. It’s the target line. If you aren’t protecting it, you are easy prey to anyone looking to attack it. Side of the head is the best alternative if the target line is protected, if not that, you go for the knees, or ankles, to try to change things.
If the asshole actually has you by the balls, you are facing a choice he probably doesn’t fully understand. Can you kill him, while he causes you extreme pain? Since he is obviously not engaged in lethal combat, you probably can. It’s going to hurt a lot. For a while. But he has one hand committed to a non lethal hold. If he is talking to you about it, he is not paying attention. Throat shot sounds like a good thing to look for. Of course you have to follow it up right away with as many lethal shots as you can land.
All of this assumes no one has a weapon handy.