So - we pushed back a bit because we seriously couldn't fathom why we'd need to remove all of the 304 functionality from the website due to a directive from the Google Ads team. 
Turns out, our gut instinct was right. The client's PPC agency ended up giving the Google Ads team a call, and then they learned that there was actually a 404 error happening (face palm) for one page. Not a 304.
Leaving this post here for good measure in case this ever happens to anyone else. Watch out for typos! 
