Well, after my talk with his Mom yesterday, she is not happy about it, but she is following my rules. I like being to help people out if it's possible, but dealing with slimy explosive liquid poop is not one of those things I'm willing to be nice about.
I flat out told her that it's ALSO about the other kids in my care and my family. I told her that even if "he's not contagious" that poo still contains harmful bacteria. I told her I had to put the kids in their high chairs while I cleaned up the mess. I told her how long it took to clean the mess.... I think she got the point that I wasn't budging.
Kudos! Glad to hear it! That's using your backbone.