I watched the video.
A real world test would have to be done on a slope not a flat surface as the CG of the entire tractor moves off center down the slope.
Because the front axle pivots, the CG will move forward when a front wheel enters a dip which is the opposite of what you would want happening
I do not disagree with your points. However, to quote you:
"wheel weights and / or fluid in the rears will help
a bit as well."
We have all seen people cutting on slopes using riding mowers and trying to sit on the uphill fender to prevent a roll over. I have seen these situations roll over when a dip in the ditch is encountered and the high operator ballast weight starts to move down the slope.
My point in my initial post was to try and make the point that wheel weights and ballast cannot stabilize the tractor to the same extend that a serious weight on the 3 pt hitch can. Wheel spacers can, on some machines that have a design where they work, make big improvements in stability
Messicks ballast chart shows a B6100 Ag tire can hold about 60# of ballast per tire.
The entire tractor weights around 1,000#
Its 3 pt hitch can lift around 40% of the total tractor weight or 400# and a properly made ballast will have this weight close to the ground and within the track of the rear tires.
The link to the prominent law suit, which was successful against John Deere who sold a tractor with no rear ballast but with a loader, will change the industry regardless of how you might view the legal argument.
John deere ballast
I spent many years in the accident investigation field and that experience has made me exceedingly cautious when offering advice where a safety concern exists. I suffer badly from PTSD decades later.
The operator of the B6100 is concerned for his safety because of possible roll over.
Perhaps all our focus should be on encouraging him to get a ROPS and wear a seat belt.
In any event, I enjoyed this dialogue, am never offended by opinions that are at odds with mine because none of us has all the answers.
Dave