How many border agents were there patrolling that border?
When it comes to reporting that the locals intend to stop paying the tariffs if the Southern states are not going to be required to pay the tariffs, I would put that in the category of "news."
Fake news?
You think the Northern people were lying about it? You think it was all bluster, and they would have continued applying high taxes to all the ships that arrived while the Southern states were not?
I trust greed in people. They would have done whatever was necessary to secure their own financial interests, and if that is reducing their taxes to insure trade with them, they would have done it.
I think you are presenting editorial commentary as fact.