So let me get this straight, their whole "investment" was moral support and a wonky promise with no clear goal of achieving it? And he just went, yep sure? Ok...
It's not like he needs their common knowledge like in other stupid mc stories, this dude lived here for 9years successfully with no problems, and if he was searching for everything related to earth "artifacts" this whole time their knowledge about them won't bring much to the table, at least not enough to warrant protecting them. Well, unless the author decides to make him not know shit and use them as exposition dumps or make them look smart... If so, 9years spent for nothing lol.