I posted a link to the SiteMonitor site where you can watch every single flight in LA airspace the entire day of the event. If you had bothered to look you would have seen that only two flights between 4:45 to 5:45 even came up from the southwest deep ocean into the Los Angeles basin. Two flights in one hour.
The relevant question is not how many flights were coming from the same direction, but how many people in the entire LA airspace were in a position to see the contrail/plume seen by the news helicopter. These people/aircraft could be travelling in any direction that would allow viewing of this from their windows.
Since some of the helicopter shots show land, it is clear that one did not have to be far out over the deep ocean to witness this phenomenon.