I would argue that the solution to this may be to make the value of having humans, or some other type of moral being, exist, be discontinuous in some fashion.

In other words, adding paperclip satisficers might add some value, but in a world where no humans (or other type of moral being) exists there is no amount of paperclip satisficers you can add that would be as valuable as creating humans. Similarly, there is no amount of paperclip satisficers that can be added that could ever replace the human race.

Now please note that I am not trying to be speciesist when I talk about humans and human values. A creature that shares human values, but isn't genetically a member of the human species, is far more worth creating than a creature that is genetically a member of the human species, but lacks certain values. For instance, an alien that had evolved human-like values through parallel evolution is far more worth creating than a human sociopath.