In the present as well as the past, many categories of people have been excluded from the left -- sometimes because of hate, other times because of inadequacy of many sorts (knowledge, resources, solidarity, etc.).
To take just one example, you stated that "During World War II when there were less able bodied men in the labor force, the disabled employment rate improved greatly." That's also the time when persons of Japanese descent were pushed into concentration camps in the USA, and few leftists -- a great majority of whom ardently supported the President who issued the exclusion order -- paid attention to their plight.
Homosexuals have been oppressed or marginalized in socialist as well as capitalist countries, and GLBT people's struggles didn't get to change things in a big way till very recently.
In the present, how many leftist publications in the United States -- including publications by, of, and for the disabled -- are accessible to immigrants whose proficiency in English is limited?
You could draw parallels between the disabled's and immigrants' experiences of left-wing politics, rather than trying to exclude the latter from the left -- or rather from this country -- while arguing for inclusion of the former.
-- Yoshie <http://montages.blogspot.com/> <http://mrzine.org> <http://monthlyreview.org/>