Mystery solved!!! In 2012 I wrote a WNP story about the St. Gabriel class of 1952, the first class to graduate from the Sunset District elementary school. Among other things, I wondered when the school mascot switched from the Gaels, picked in 1952 when the days of St. Mary's Gaels as a football power were still fresh in our fathers' memories, to the Knights. No one seemed to know when or why. Some of us old timers thought it might have something to do with being culturally insensitive. Hey, Stanford kicked the Indian off the reservation. One wit said it was because few people knew what a Gael was. In 1952 I thought it meant an Irish knight, so perhaps the switch to Knight was logical.
Recently it dawned on me that I should put the WNP post on St. Gab's Facebook page which drew this answer from Charlene Shaw McDonnell, who was a teacher at the Catholic school in 1978 when students decided to select a mascot: "No one knew of any other names," she said. "The Knights won and we have been the Knights ever since."