There can be many scenarios but something is off the charts.
First of all Sartre, in my personal opinion he's not the average guy who get's hacked, he know his stuff and surely have all sort of authentications and this is what scares me.
Also, he's not the type who comes here to build a trustable profile to scam some people with a marketplace sales thread like some examples we have seem around here over the years.
I really believe he must had offline backups and someone tracked him down and he got him kidnapped or some shit and someone it's impersonating him to "keep it normal" (what did not work because people know how he talks and he have his own behavior that canot be replicated) while it gives him/them time. Time they need to actually get access to his backups, bank data, authorizations, things that have a process and take time to actually have access on.
All this of having the phone off and all that, it's not normal at all. If he got just hacked he already contacted a friend to let at least bhw know his fine.
I hope this guy's alright, for real.