What's subversive about it is that if she'd not used the word "retarded" her routine would not have had impact.

There is a sense in which PC language suppresses the real struggle that comes with difficult social issues, sterilizes them for us, and makes them into abstract problems that everyone can claim to care about but do nothing about.

Silverman's insight was that by breaking out of the PC mold she was able to shine the spotlight on a difficult social issue.

Is it the highest level of subversive comedy? Probably not, but it's certainly a courageous form of activism.