If you're taking a shyt and a nikka shoves his dikk in your mouth, are you going to wait til you finish, wash your hands and dry off before you start swinging?
So I guess I'mma have to get all biological on you and shyt
The rectal sphincter is a lot easier to clench shut than your prostate. Therefore just because you upper cut dude that doesn't mean shyt will fly everywhere. But taking a shyt you're in a much more vulnerable position than standing pissing. So it's justified if you react more violently.
However, it's all about reacting appropriately to the threat in a public environment. If it's 3am and you're alone then yes you should cold cock the nikka without any hesitation no matter what.
But if it's 12pm and kids running around outside and nikkas in and out of the station then I think it's OK to pause after verbally commanding the nikka from invading your personal space. The problem is you have to deal with legal issues when there are by-standers and witnesses.
If it's a situation when you know no one will come and you can have time to clean up the piss or shyt off your clothes after the altercation - Then by all means fight the nikka with your bodily excrement flying everywhere and knock him out cold.
It's a shytty situation to be in but since you insist, another thing that would help is planning ahead. I'll never be caught in this situation because I take my shyts in the morning before I leave every day. Don't take shyts in public bathrooms.