NavList:

Frank, you asked, “Was the clue about a nearby star the key?”
The giveaway was 12 light years, Class G.  Googling ‘Nearest stars’ gave Tau Ceti, which led to Cetus, which led to Diphda or Menkar.  Then the launcher still perspiring like a steeplechaser in the Winner’s Enclosure suggested post rather than pre-flight.  No9 is written at the top of the launcher.  Googling list of SpaceX landings gave one on LZ1 on 25^th, the date of the Facebook post.  I was unable to find at which time the launcher landed, so I went to ‘Navigator – Star Finder’ and looked at each hour from 00:00 UTC to find when Diphda and MenKar were at practical heights while it was still dark.   Diphda just fitted around 0900UTC.  Menkar was too low.
I was struggling with scale, and I guessed Saturn at alt 45° 41’ Az 126° was just out of shot and identified it as Ceti I making a triangle with Ceti H. 
It's a pity I missed Saturn, because it tells you almost exactly where the photographer was standing.  He was standing a distance almost equal to the height of the launcher on a bearing of 306° from it, so the lightning storm must have been out at sea. DaveP