It's the same way with other frivolous suits, shake downs or attempts to get something for free. Our local airport tried to pull that off and in the wake they trashed most of the good will they had in the community. Problem was, one guy (yours truly) wasn't budging and helped organize the other victims. Then we told them to come and get us, followed by some media exposure. As a last act of good will I sent them several pages evidencing why they'd lose a court battle but that I'd be willing to fight. Boy did that change their attitude. So no, you don't have to back down when someone tries a patent lawsuit that is obviously meritless. I certainly wouldn't.