Any thoughts that he, his family and friends were not hiking enthusiasts, therefore, making it harder to locate within the hiking community? I don't think he was all that experienced in hiking. It was a bucket list opportunity and he went for it. Also, in all honesty, how many former co-workers have you ever looked for? I have never looked for any of my former co-workers after a period of say, three or four years. I'm just throwing this out there. They may not be looking for him, and his family maybe doesn't even know he went hiking.