Love the notion but women wearing that sort of teeshirt are in for a ton of sh*t from people who don't understand or agree with the message. I could see them getting jumped by certain hotheaded groups. "Uncle Tom" is pretty inflammatory and for a white woman to adopt it might send some over the edge.
Feel better?
Would help to post the twatterer - this link just sends to the website without indicating which thread. At least it does for me.