I know of a guy who was building a -7 with rivets and polysulfide. I believe his rationale was that it would provide improved corrosion resistance at the lap seams. He worked for a biz jet manufacturer that used the same process (as I recall to make the fuselage air tight for pressurization) so he was prepared for the task. I also saw a BD-4 under construction that used polysulfide and pulled rivets. I don't know much about that aircraft, but was told by the builder that sealant and pulled rivets were done in accordance with the plans. That being said, it adds weight, cost, and time to the (RV) airframe.
Some years ago, I used polysulfide and rivets to attach the stiffeners to the skin of the (2nd) rudder I built for my -4.