You didn't even need to say they were medical records. Grab them, call for a supervisor, and have a lively discussion about looking for WEI.

They could be love letters, financial records, confidential legal papers, notes on a book you're going to write about TSA abuses. None of them can even be REMOTELY claimed to look like WEI on an x-ray.

You were right to shut down the fishing expedition. Please follow up.

One perfectly acceptable answer to the "what is this" question is "It's not WEI." Whatever answer the passenger gives, the screener shouldn't be allowed to give it any weight. Items are either WEI, or not-WEI, and the bad guys would ALWAYS answer "not-WEI" if asked. Unless they were from that mythical island where one tribe always lies.