I’d bet it’s closer to your theory than the usual “ROP” exclamations.
Moslems aren’t interested in giving warnings, and they really aren’t interested in minor airports. They tend to start big.
If it’s a Moslem, he’s probably doing it on his own recognizance, not coordinated with any big organizations.
About the disgruntled ex-spouse...
Why would there also be a threat made to the other location, if it were just the guy/gal in L.A. area?