Swift Aire was the airline based in San Luis Obispo. Golden West was based elsewhere in Southern California, I just can't remember where the HQ was right now. I also believe it was 1985 that Golden West closed its doors.
There are no remnants today. As far as the circumstances, I'll have to do some digging but my memory seems to be that they were simply a casualty of the post deregulation wars in California, along with Swift, Apollo, Golden Gate and others.
I.E. Quastler of San Diego State University has chronicled the commuter airlines in that era in several books, most out of print. You might find information in a used copy of one of his books.
"Travel is fatal to prejudice, bigotry, and narrow-mindedness." - Mark Twain