If he bothered to check....
And that's the crux.
The current "smoking gun" is the "hidden" footage that Sibrel shows in
A Funny Thing..., and how great it was that he presented the footage. Yet as soon as he was corrected, in that the footage HAD been shown/available almost since they got back, it was suddenly all "well, I always meant that we can't take Sibrel literally, but...".
Hell, one of his 'issues' is that the view rolls near the beginning, and surely this isn't supposed to be them rolling the CSM (as if they would waste fuel on that) when the transcript gives the quite clear impression that they rolled the camera. Or that the windows, when the view is interior, are blue, so it must be "sky" (inferring looking at Earth), because it's not black. As far as I know, this is an artifact/combination of the light reflecting of the coatings that were applied to the glass and the gas used between the panes. And the simple point that glass is pretty reflective when the interior is lit and the outside is 'dark'.