I think non-abstract non-universal moral principles mean a warm fuzzy feeling inside. I suppose such private principles can, possibly, be derived from vulgar liberalism: "Do as you please as long as you don't hurt others." But that would get confusing since in practice moral principles are only fun if you can use them to point a finger at those who don't live up to those "non-universal" principles which don't apply to those who don't follow them. As you say, it's a bit confusing. If P's non-universal moral principle only applies to P and friends, it seems a trifle odd for them to go around objecting to Q's failure to follow the non-universal principle which because it is non-universal doesn't apply to him/her, so why should he/she follow it?
Carrol