That makes sense. I think it’s either, as you say, the BF ‘s arrangement, with Gold as the middleman, or Rumple, when he learned Emma’s name back in FTL, was able to see her future and, then knowing about Henry, planted, so deep into his psyche that the curse couldn’t erase it, the command to bring Henry to SB.
Mostly, though, I think it was a mistake in the writing. 😕
However it happened, I think Gold talked Regina into the idea of becoming a parent.