This guy was pretty active in the classified. His address should be known? Many people mailed him stuff and received packages from him as well. Mailing address (if just po box) would still be useful to track him down. Even phone number - someone mentioned texting him. People sending him packages would have had to fill out customs forms.
A PCFer mentioned he met poppin at the dirt bag's house. Not sure which of the related threads this was noted.
I believe it was
@Lemonzest who knows his LinkedIn profile - so employer and coworkers can be contacted. Poppin likely has social media (FB, IG, etc) that can be used to find friends and family.