huh, looked it up and turns out shooting him in the **** does indeed work. thats my new thing learned for the day.
tbh, i think you're putting way too much thought into that mission. i just shot him in the face till he died same as the hoardes of nameless bandits, robots, soldiers, wildlife (endangered or otherwise) and frankly anyone else who had a health bar in need of draining.
i mean we're talking about a video game series that at one point asks you to blow up the ocean, it's not meant to be taken seriously.
I googled it and first result was
https://store.steampowered.com/app/469820/Genital_Jousting/
There's a steam game called genital jousting