I used to abide by this until it dawned on me that malicious people often use stupid people as a cat's paw to conceal liability. A careless disregard for the truth is itself a form of dishonesty. This argument is laid out very effectively in philosopher Harry Frankfurt's delightful short book On Bullshit.

I agree, but in this case stupidity can not explain their actions.

The agency processing the FOIA request would get the export control status from the third party I contacted. The third party's software highlights export controlled documents with a red and highly noticeable statement. It would be difficult to believe they thought this was present when it was not.

The request also had actually been transferred several times because no one believes they have the authority to release the document I requested. The other agencies had ample opportunity to reject the request for being export controlled, but none did.

There are some other reasons that I will omit for brevity.

This makes me think that the export controlled claim was a lie meant to kill the request. Most people would stop at what they told me, but I thought it was worth verifying.