It’s an easy mistake to make. Just keep your yeast in a labeled* Tupperware container in a different cabinet than your sacrifices. And remember to thoroughly clean all utensils.
* That time I mixed up the yeast and some aromatic powdered herbs for the sacrifice - what a mess! Luckily, She must have been in a good mood that day, so no plagues.
But those are not universal moral laws any more than the “usual” list of ten commandments. Non-Jews/Christians may not be into murder or torturing animals, but someone still managed to sneak in a few lines about worshipping the correct god. Still unacceptable for public display.
At any rate, the actual answer to the question “why those Ten Commandments”, is “because those particular Ten Commandments are what the people behind this want to post in schools.” It’s always about pushing their exact brand of Christianity; you shouldn’t expect any deeper answer than that.