My two cents is no, I wouldnt.
It's just a handful of spot welds holding some panels making contact together. Adding partial seam sealers on certain joining surfaces only increases the likelihood of water being redirected somewhere it otherwise wouldn't have been, and /or trapping said water once it makes its way there.
As far as rust starting, it comes from a number of places. If you have the weatherstrip and/or window trim off the car you will see gm applied some seam sealer, the application being of varying quality, in the corners near where the roof skills and quarter skin met. Water can, and did, enter there along with places like drip rail caulking, humidity condensing and dripping down, so on so forth, all of which aided certain cars in rusting.
