Hi Dave, I do not know anything about this except that I also have a Sargent, and yes, it is reversed. I always assumed it was like coke versus pepsi: if one is red the other has to be blue. If Stanley adjust this way, Sargent will adjust that way. If anyone knows anything I would be interested, but I do not think there is any real reason that the adjuster ought to work one way rather than the other, other than tradition. In any event, I like my Sargent (though may favorite is a particular Stanley #4) and just put up with constantly being confused about about which way to turn the knob, or, for that matter, which way to turn the Stanley knob after I have used the Sargent a bit. No big deal, especially since at my age, I tend to be confused about most everything.
Oh, my frog is a replacement. I bought it years ago just for the heck of it, before I really did any woodworking. I knocked it to the garage floor and shattered the frog. Oh well. I saved it in the corner of a drawer somewhere until some clever people invented ebay, and surprise, I was able to find a perfect replacement frog at a not too horrific price.