If you send cease and desist letters without merit you should be forced to indemnify the respondent for the entirety of their attorney's fees and pay exemplary damages.
This would require lawyers to make a careful assessment about prospects of success, rather than hoping to scare the other side into capitulation.
These heavy handed tactics are just dreadful and shouldn't be accepted in any rational legal system.
To avoid doubt, I'm not saying that their claim doesn't have merit. Unfortunately you will need to pay a lawyer to find out.