Epic CS Failure @ LAX - AE pilot only employee who offered help
As said earlier, I was on the same flight, and why the flight could not land in SLC perplexes me as well. The pilot said that due to fog, an IFR cat III landing was required and the aircraft was only equipped for a cat II landing. I don't know much about the avionics of various aircraft, but it was a brand new CR7. The Delta/SkyWest flights were on CR2s and were able to land fine in the light fog.
I think the aircraft usually goes ORD-SLC-LAX so that may be why they went to LAX, but no passengers would have been ticketed to LAX.