Why un-grammatical if no action verb precedes "in response to"?

What "verb" must precede in response to? Why in response to incorrect "without a verb"? I think authors made mistake, because "were" IS a verb? Just not ACTION verb?

response, as in in response to. This phrase is often used incorrectly without a verb, as in the following sentences: The regulations were in response to the problem created by lack of definitions. Rather, state that the regulations were enacted to resolve the problem. Board Letter No. 829 was in response to an inquiry about disclosure of a security interest in all after-acquired property. Rather, state that the letter addressed disclosure of a security interest.

Bahrych, Merino. Legal Writing and Analysis in a Nutshell 5th edition (2017). 375.