Thanks, SillyLilly, excellent find. Don't think I've ever seen that post before.
Strange to see raw onions in the 'completely safe' category. They're definitely antibacterial, especially right after you cut them. I suspect he didn't chop them up fine or puree them, but instead used thick slices or chunks. As solids, they would only affect the bacteria immediately enveloping them.
Raw garlic is one of those things you have to be smart about. IMO, if you slice it thin or mince it, all its germ-killing abilities get used up in your stomach or small intestine, then from there on down its fibers serve as a prebiotic. But if you swallow whole cloves you run the risk of big, intact pieces making it all the way to your large intestine where they would kill flora indiscriminately... Helpful germ-killer as long as you limit it to the mouth, stomach, and small intestine.