David Wagner writes:

Given this risk, I've decided I cannot afford to continue to work in the area of copy protection as long as the uncertainty remains. And how in good conscience can I advise students working with me to work in this troubled area? I can't.

It's understandable that you would be concerned about the DMCA. Niels Ferguson raised the same issues when he decided not to publish. Why, then, did you go ahead with publication? This is the part which is hard to understand. Niels decided not to publish, you and your co-authors apparently came to the opposite conclusion. Rhetorically you are saying the same things as him, but your actions are different. It would be interesting to hear more about how you reconcile the decision to publish this result with the belief that the DMCA makes publication in this field too risky.