Kutter, I have modeled up your concept and it does work however it has one negative that I am not sure I like or not. Depending on size differences of the major diameter of the pin and the groove diameter in the pin and then the amount of distance allowed between the centers of the offset diameters in the blade when the sight id fully assembled and the blade has popped up into the groove there will be a gap at the top of the pin that would so to speak let light shine thru from the side. Now is this an issue, I really don't know. How big is it well lets say if the major dia of the pin is .160 and the groove is .150 which would give a .005" retention of the blade which I believe is enough. And the offset of the holes in the blade is say .007" so you have fit clear of and extra .002" then the gap when assembled at the top would be at its worse .007". Tapering to nothing 90 degree toward the front of the hole.
Here is a pic. This is a bit embellished to enhance the issued. Actual dimensions given above would have a little less gap. Now first question did I understand your concept correctly?
[Linked Image from i.imgur.com]