Another thing I thought of…would she even be compelled to grant him his favour? Regina’s not compelled to comply to the “please” any more, so could Emma just refuse to do whatever Rumple asks of her if his deals aren’t quite as iron clad in this new world? Though I suppose he could play on her maternal instincts to convince her to help, if he does in fact want her to find his son.
I think Emma will grant the favour because of her own sense of honour. Even if she refused, she would still owe Rumple and that’s a position nobody wants to be in. I think Rumple’s favour will be reasonable enough for her to do.