I think the decedent theory makes more sense when you think about it chronologically.
What happened with Hook, Milah’s death, it happened 300 years ago. Bae was only 7 years old when Milah left and Rumple became the Dark One 7 years later. His father would have most likely been dead for a long time by the time he got out from Neverland. Unless, yes, there was a curse like what happened in Pirates of the Caribbean. But decedent makes more sense.