For the same reason you actually took the time to read the article.
In other words....they didn't.
No Russian Commie is going to invade San Francisco. First thing you know, their tanks are painted in pastel paisley flowers with Daffadilos hanging from their gun barrels.
Then a bunch of gay mimes will make fun of Putin.
Next the Flaming Faggots will moon the Russies, making them puke all over their weapons.
Then Ellen DeGeneres and Rosie O’Donnell will come out and tell some jokes. That will have them rolling in their boots with laughter.
And lastly, California’s secret weapon, weirdo Hilton Perez will come out and kiss the Russkies, thus assuring their death by barf suffocation.
That is why the Russians ignore California. They’ve got enough problems in the Motherland to work on. Why occupy a disease known as San Francisco?