You should give them a friendly reminder that removal or alteration of, or false provision of, copyright management information, is a separate offense under the DMCA that they can be liable for.

(IE you could commit no copyright infringement, and still be liable for removing/altering/falsifying the CMI).

see https://www.law.cornell.edu/uscode/text/17/1202 and https://www.law.cornell.edu/uscode/text/17/1203

Unlike their hilarious reverse engineering "reminder", fair use is not a defense to this.