Maybe it was an attempt to avoid exactly what happened - reporters, rumours, digging into his past, and accusations. Though I don't know why they might think it would work. Just a thought.
If my child was missing, the last thing on my mind would be protecting the reputation of my grandfather's friend, who I'd never even met before the day my son disappeared. In fact, I would do whatever I could to make sure he was thoroughly investigated and provided absolutely every smidgen of information he possibly could to LE. (Of course, it's likely he was cooperating, but I wouldn't make any extra effort to protect this virtual stranger's identity.) It seems like telling a story about how your child disappeared without including 25% of the adults there at the time would take extra effort. JMO.