This compound protects by preventing moisture, preventing oxygen and preventing the dis-similar materials from direct contact. If one of those “barriers” breaks, there are two more. Real life experience has shown that it works just fine, but it is a messy process to apply, it’s also time consuming.
I can guarantee that no compound will break a conductive path between the rivet and the substrate. Especially when the rivet is compressed, which rivets generally are 
But yes if keeping oxygen out is enough, that will work. Socata use “wet riveting” on some airframe sections (skin to ribs AFAICS); this is messy since the 2-pack PR sealant goes off in an hour or so so you have to work fast.
Private GA is different. They can easily be protected well enough by simply storing them in a hangar, or even better, a heated hangar.
That helps a lot (heated hangars are incredibly rare) butonly delays corrosion.
There are a whole bunch of “snake oil” stuff (sprays and stuff) that do actually work very well by preventing accumulation of moisture, and some of them also have corrosion inhibiting pigments of some sort.
ACF50 definitely isn’t snake oil – it is brilliant stuff. But messy…
