I think Rumple “taking Lost boys with him” doesn’t mean freeing them. The lost boys work for Peter Pan so Rumple’s saying he’s going to die and he’s taking as many lost boys with him as he can.
Hmmm, certainly a possibility, hadn’t thought of it like that. He’s going there on a rescue mission for Henry, so if he’s trying to set one kid free, I hadn’t considered that he’d wipe out as many other kids as necessary as collateral damage.