Open source community needs to aggregate a list of lawyers who will consult on these sorts of things (related to the community at large) pro-bono. This way all parties on the open source side can feel a little less pushed around and bullied and a little more protected.

The best part would be to learn that the claim was not valid in the first place. At the very least, having representation would provide for some wiggle room where you can have days if not weeks to resolve the issue, instead of feeling you have to take immediate action.