Paranoia runs deep these days for people who don't like seeing so many brown skins or slanted eyes. They suspect anyone speaking a foreign language is really gossiping behind their back. Maybe they envy your ability to speak Spanish or God's gift of multiple cultures.
Maybe it's an "I got mine, the hell with you" attitude about those yearning for a shot at the American Dream. Change scares them.
The White Power author would love to goad us into his sewer with a fistfight. He enjoys attacking the very fiber of our ethnic heritage. This particular letter attacked Latinos. In the past, Jews and blacks were targets.
Perhaps the best medicine for this racist's sickness is the bitter pill of seeing all those "Mexicans" at Santa Monica High graduate, driven by the desire to live the American success story and their refusal to be sidetracked by a moron's vile invectives.