It hasn't lost meaning at all, it's just that some people don't like the meaning so they misrepresent it or pretend not to know what it is.

It basically means hypocrisy and/or insincerity toward popular progressive causes. That's the meaning. There's also an older one which has mostly been displaced as far as I'm aware, but if it's still used it also has a pretty well defined meaning. In context, at least in this context, it was not ambiguous which meaning was being used.