They'll agree to his deal in exchange for the trade route and leave the investigation at that, unless the guards have something else they'd like to press him for.

They are definitely interested in following up on this clue and would want to ask around with the merchants. That name certainly caught Natasha's ear since she's been tracking the rumors and speculation about Josselyn since overhearing about her at the negotiations and starting to look into her back then.

Spending some coin among the merchants and otherwise using Natasha's investigating/coercion skills, they'd try to find out what the merchants could tell them about the Creed family and the merchants' dealings with them?