I think Rumple is not a coward for leaving the town. He can’t stay oteherwise he kill Hook and he want to be at least the man Belle wanted him to be. His staying would only hurt her, because he will not stop to heal her from the amnesia and would destroy something else on the way. His desperation is dangerous. He needs his son.
The threat altough was really something a real coward would do. He could have asked that the Charmings to protect Belle, but he was afraid that they would say no, like he did with the outsider. He don’t want to owe the something.
I really been interesting in the next few episode for the developing of Rumpelstiltskin. I mean not many fathers who abandoned there child would try to search them and ask for forgiveness. My own father didn’t. I think how he will handle this situation we will see how much coward he really is. I mean Bae ist the person he love most, will propably hate him like no one else. I want to see the reaction and then I can say he is really a coward until now.
Heros don't get their Happy Ending!