The article linked in this comment states that a local pastor gave him a ride to Weed, to a gas station, and that surveillance video corroborates this.
My opinion is the most likely gas station would be the truck stop, which is a massive hub of semi-truck traffic. It is not in Weed proper, but south of it by a couple miles. Hundreds of semi-trucks go through there every day, as it is the only real truck stop between Redding, CA and Medford, OR. It would have bee easy for him to attempt to hitch back to SF from that truck stop.
Makes me wonder if he crossed paths with someone at the truck stop in Weed. Also wonder if there are other missing persons along the I-5 trucking corridor, especially men, and especially black men. Over the past 10 years. Any way to search for that?