Any guy who enjoys her mouth on his dick ought not to be grossed out by his ejaculate getting into his mouth. I've tasted my jism directly and indirectly and have no problem with it. Our juices are often quite mixed: saliva, her wetness, my precum, sweat, semen, even milk, you name it, it's been shared in kisses, on fingers, and served with smiles.
I don't understand or get the appeal of snowballing, by itself, as a fetish. Seems like trading gum.