Yeah, I bet Rumple knew what was coming, and willingly walked into the trap Cinders tried to set. Perhaps he wanted to be imprisoned in a magical mine to be protected from the EQ’s curse. Perhaps the fairy dust/magic wooden prison bars shielded Rumple from the dark magic, thereby preserving his memories of FTL when he was transported to SB with the rest of the bunch. Also, he probably foresaw Snow White would only come to him for help about the curse once he was safely behind magical bars. That way, he was able to strike a deal with her: knowledge about the curse and how to break it in exchange for her unborn child’s name: Emma. We already know that for Rumple, knowing someone’s name gives him power over that person. Now in SB, Mr. Gold may have that power, plus Emma owes him a favor in exchange for allowing Ashley to keep her baby.
"That’s how you know you’ve really got a home. When you leave it, there’s this feeling that you can’t shake. You just miss it." Neal Cassidy