Because Teflon is harmless to the human body. It is inert. It interacts with nothing. We literally make replacement body parts out of it.

This is a case where conventional wisdom on HN is wildly out of sync with actual science.

Drink a pint of it then?

Just because it's inert doesn't mean it's harmless. I'm pretty sure that if you shove a wad of it in your windpipe, you won't last very long. Also go check out water poisoning.