No, I'd be p*ssed at her, but then I'd be p*ssed at anyone who ran into the back of me whilst crawling along in traffic. It takes literally no effort at all to crawl along and use your knees to steer a fraction to stay in a lane. You really don't need to use your hands at all, AT LOW SPEED AND IN A RELATIVELY STRAIGHT LINE. Give it a try, you'll see how simple it is and how little control it takes away from the driver. As long as you're concentrating on what the car in front is doing, it's really not difficult to do.
Again, it's not right and she shouldn't be doing it, and maybe if the cyclist hadn't been so militant I wouldn't be sticking up for her so much. But he did, and it annoyed me, so now I'm digging myself in.