Context for Zenos: For Zenos, the “wilderness” in which he resided would obviously have been in the Old World rather than in the New World. His enemies were the enemies of Israel. Sorenson has speculated that the brass plates were a Northern Kingdom record (John L. Sorenson, (Sorenson, John L. “The “Brass Plates” and LDS Biblical Scholarship” undated mss.), and so the wilderness here would have been north of Jerusalem.
Context for Alma’s discourse: Alma is preaching to a people who are not city dwellers, but farmers in the outskirts of the land. While they are not in a wilderness area, they border on a wilderness. That would be sufficient to have a conceptual connection between the physical location of Zenos and these particular farmers. This verse speaks of prayer, and prayer outside of the city center, which is precisely the message that Alma has been trying to teach.