The phrase "Bury the hatchet", as discussed in this episode, refers to the literal burying of a hatchet to symbolize making peace and cement it among Native American tribes in the eastern United States as seen by Young Ian.
In tarot, the hanged man doesn't mean a person who is to die or anything so macabre. In fact, it is interpreted as a person in stasis, contemplating the world from a different angle (not necessarily a good one, but different). It signifies surrender, pause, a choice. Or, reversed, it signifies delay, restrictions, indecision. Therefore it does, in fact, apply to Roger, and not in a literal sense.
Roger wonders if he's meant to exist because his ancestor almost killed him. In the books he does not know it was Buck that ordered his hanging until much later.