My recollection is that it transports you right outside their gate, which will be locked until you do that quest. So it would work but maybe not achieve the goal you wanted? I think you can also get provisional permission to trade with a single one of their merchants without doing the quest if you ask nicely. Super good game though. Lots of wacky things you can get to work, like that, depending on how lucky you are and how badly you want to break things.