Something being stinky or something being a germ doesn’t mean they can harm you. Lots and lots of bacteria exist that can’t hurt you that you’d find in a digestive tract, and maybe a few that could, especially if you ate them. Beyond that, lots of things like scent particles are airborne but not all harmful germs are airborne so again, we long as you don’t consume them, they’re not going to harm you.

If something was coming out of your butt that could genuinely harm people just from inhaling you would likely be a very sick person with a pretty rare and probably very scary infection, if such an infection even exists.

Lots of the stink from the digestive tract is also not from germs at all, that’s just what food smells like once it’s broken down, same as if you left it in the fridge and it rotted and got stinky.