Also how many microbes (because mako used number of actual organisms per gram to make his numbers big and scary) per visible colony or growth that you’d see on a plate with food that’s been left out for several days.

What he should have elaborated on, instead of only a single sentence with a curse word for emphasis, is that the microbes in your fecal matter are more likely to be able to survive inside of your body if they make it past your innate defenses when consumed. They were already in one area and survived, and now they may be entering a different area (which is one of the major ways infections can happen). You have plenty of microbes happily surviving on your skin, in your digestive tract, etc. without causing any issues, but if they make it elsewhere, some pretty nasty infections result. Look up Staphylococcus epidermidis and its outcomes for people who have plastic medical devices implanted, even though it’s really great for you to have it on your skin.