oppression vs exploitation, and the liberal limit on "classism"

From When we say "class", what are we talking about? | libcom.org: 

The resolution of problem of “classism” is essentially liberal. This isn’t necessarily a criticism. In the here and now, I don’t want gay people to be discriminated against. But I’m basically demanding that liberal democracy does what it says on the tin and treats everyone as equal, sovereign subjects. The same goes for racism, sexism, etc. The culmination of these politics is formal and informal equality as liberal...