I'm not sure I would build it in InDesign but if I did I would save it as a PDF (or export it as the case may be) then open it in photo shop, flatten it and save it again as a PDF. From there I might open it in Acrobat, do what I could there.
Then I might even take a printed version and scan it as an uneditable PDF.
Given the importance of the document and the nubmer of people that would scutinize it it seems really sloppy. Someone was expert that put it together, just not expert at covering their tracks....
....or they purposely did not cover their tracks as in they wanted people to know.
I think the problem was that they were trying to get Donald Trump to back off, so they rushed to get something out to the public, knowing the LMSM wouldn’t ask questions.