Well, we've already drifted far off topic... why the hell not. I'm going to hide-box it because it's so far off topic.
The Problem with Circumventing Hingan Tariffs
It'll send Kugane, at least, down the toilet. Turn it into the Detroit of Hingashi!
Kugane is a port town - it makes most if not all of its revenue from the tariffs Lolorito and Rowena are trying to get around. Let's assume they do get that trading post set up on Eureka. If that happens, it won't just draw away the Eorzeans' business - everyone doing business in Kugane with intent to spread their goods further abroad will be compelled to use that port instead for everything but imports headed to Hingashi itself, assuming Eureka's tariffs are lower. Without that tax revenue, Kugane won't be able to sustain itself - or at least, not at the rather opulent levels it's presently at. It would essentially allow the EATC and Rowena to price gouge imported goods in the Othardian region due to being free to set their own tariffs.
Depending on how far Kugane's tax revenue reaches, that could have a wide-reaching impact on Hingashi as a whole. Since it's funded in part by Lolorito's EATC, and Lolorito holds a position of high governmental standing in Ul'dah due to his wealth, it could lead to a conflict of interest - is he doing this for the sake of Ul'dah, or as a private businessman? (Most likely the latter.)
However. The accusation that "Eorzea is adopting imperialist practices" and "attempting to start a trade war" is a gross exaggeration of what's actually happening. A couple of privately owned businesses (one of which is, admittedly, connected to an Eorzean government) are simply doing what's in the best interest of their business. Businesses exist to turn a profit, not give foreign governments record revenues through exorbitant tariffs - if they see a chance to increase their profits, it would behoove them to take it. If that comes at Hingashi's detriment, so be it - they are businesses, not charities. The accusation also reaches far beyond the people it should be levied at - it's two people and their companies, not Eorzea as a whole. The majority of Ul'dah, and all of Limsa Lominsa, Gridania, Ishgard, and Ala Mhigo have nothing to do with it at all and, in all honesty, probably do not care much since it's unlikely to impact them in any meaningful way.
Furthermore, as Kugane is the only port open to foreign trade in Hingashi... again, it will likely go down the toilet unless it gets competitive with Eureka's tariffs, but the rest of Hingashi should be fine. The entire country was closed to foreign trade until relatively recently, if I recall correctly, and the wealth generated in Kugane through tariffs likely doesn't reach far beyond it. Kugane's streets might not be paved with koban anymore, but the rest of the country should get through it no worse for the wear.
There. I acknowledged the nuances. Press the issue and I'm likely to come up with a Chewbacca Counterargument, for my amusement!
So I suggest it die here. Red Herring, thou hast fulfilled thy purpose. Pray return from whence you came!