Article says that helicopter was twin-engine, and that catastrophic failure of both engines would be highly unlikely. It also points out that it was unusual for such a helicopter to have only one pilot, but surely pilot medical problems would show up in voice data.
Why did the pilot turn south when his presumed destination, in Thousand Oaks, was to the west?
He was IFR (I follow roads) @ that time, he wasn't flying direct in that weather so either the road was trailing south or he was trying to avoid the high ground or obstacles (wires). Or he got disoriented in the weather, struggling to maintain clearance from clouds lost the bubble entered an unusual attitude/vertigo/and crashed.