It’s written in the modern clickbait style- they tell you that you’ll never believe something, then they string you along as long as they can. It’s frustrating to read and usually ends up being mundane info. Usually by the second paragraph you can spot this type of writing and need to be ready for disappointment.
I’m not sure that the whole command/service module separation issue was actually classified, or if it is just a less commonly known part of the story.
Apollo 11 Mission Anomaly Report 3 - Service Module Entry
Conclusion
Tip-off moments applied to the service module at jettison cause the spin vector to be misaligned with the service module X-axis. The rigid body spin motion of the service module excites longitudinal slosh of the propellants in tanks. The sloshing then becomes the dominant force and causes the spin vector to approach a position normal to the service module X-axis. The sloshing can orient the service module spin axis such that the net -X thrusting over a period of 300 seconds can not only reduce the separation velocity of the service module but also reverse its direction. This condition introduces a remote possibility of recontact between the service modules and command module. An optimum separation velocity can be obtained for a range of propellant loads by restricting the spin thrusting to 2 seconds and the X-axis thrusting to 25 seconds of firing time.
I don't know who said it first, but we see a lot of blog posts that could have been condensed into tweets, and a lot of books could be condensed into a blog posts.
I’m not sure that the whole command/service module separation issue was actually classified, or if it is just a less commonly known part of the story.