The rest of his body of work looks very real...
and that accounts for allot in my opinion YMMV.
I am just making some observations from a non-expert viewpoint:
The use of HDR (High Dynamic Range - 3 or more Exposures without horizontal shift that have been merged) could be very problematic with Aurora (too much movement). However RAW HDR - One exposure that is RIPPED as over and under exposed post production can be merged for work that looks similar to the above...
The Star trails are very short (if at all) but the headlights/streetlights are merged...
This suggests a under 20 second exposure and the aurora is very clearly delineated in the vertical...
Looking at from a RAW HDR standpoint I don't doubt its authenticity.
However in my opinion astrophotography is the one of the hardest of genres out there.
and seriously I could be 100% wrong.
Randall