Getting to the trader is not the issue -- it's once you leave Fort Joy Dallis' event at the front gate triggers and everyone leaves, so in that respect you are limited.
Besides that words like achievement, challenge, and even exploit are subjective -- each player has their own definition that varies from yours or mine. That's why I don't mind doing stuff like the One Man Army challenge or defeating Dallis at the start, because it means something to me.
