There's a difference between a metaethics and an ethical theory.

The metaethics sequence is supposed to help dissolve the false dichotomy "either there's a metaphysical, human-independent Source Of Morality, or else the nihilists/moral relativists are right". It's not immediately supposed to solve "So, should we push a fat man off the bridge to stop a runaway trolley before it runs over five people?"

For the second question, we'd want to add an Ethics Sequence (in my opinion, Yvain's Consquentialism FAQ lays some good groundwork for one).