Evidently, Shaw was highly paid, and was not a CIA officer, but a source. That is what the CIA historian said, and in writing, and not in a memo, but an official report. This seems like a hard one to dodge.
I had the misfortune of working in a government office in the late 1979s, and anything in writing is scrutinized carefully, and I assume more so at the CIA. One reason is that government offices are very political, and also do not have budget constraints and tight deadlines like the private sector.
The government agencies can and do copy-edit through layers and layers of officialdom.
In the private sector, there is a budget for a thin line of copy-editors, and the product has to get to press (old days).
If you look at the "masthead" of the CIA report, you see a lot of names.
I cannot prove the CIA historian was accurate in his description of Shaw. I would put high odds he was. That's kind of sensitive matter to get wrong.
But, as I say, caveat emptor,, and draw your own conclusions.