how can a proposition of "moral absolutes" be anything but all or nothing?
Buried in your objection is a defense of moral relativism, which is THE problem, and I might add, that which excludes one from the class of "conservative" -- as that class is by definition those acknowledging Natural Law (as absolute as it gets) either explicitly or implicitly by acknowledgment of the founding principles and documents as a Supreme Law.
It can't. That means that unless you can make everyone agee to and abide by your moral code, you've failed. If you can't get it all, then by your account you have nothing, and you will never be able to have it all.