> But there's another truth to it that the article also describes--if you agreed to work for a wage and then receive that wage, can it really be called unfair?

You define what's fair based on what information you have. If new information reveals that trade was not only unfair but a blatant rip off you are within your rights to feel something about it.

Still, I think one should accept the past trade. But there's no reason for that, combined to the new information to guarantee a continuous relation.

In other words, renegotiation based on new information that substantially change the deal is moral.