I think the rivet pull out looks higher because they test it through two thicknesses of sheet metal, whereas the rivnut is tested through one. In all cases, the rivnut will have more surface area to hold the panel because of its larger diameter. The rivnut also will have much higher shear because of the greater cross-sectional area, especially when you consider the 1/4" bolt in place as well.I don't find a apples to apples comparison in pull out strength.
The rivnut can be recompressed by tightening the bolts. The pop rivets are compressed once and then the mandrel breaks. Repetitive motion will eventually pry them apart, which will then lead to motion that will shear them. If you extend your brackets a bit you can get two or more rivuts along the truss, which will greatly improve your chance of holding the panels in place.
One additional advantage of rivnuts is that you can easily remove the panels for maintenance or upgrade without having to leave the angle brackets in place.