I really have not found or mounted a pivot door frame that worked 100% correctly. I really love the doors with that piano hinge system down one side.
You also must not have a shower dam wall, or a 5 inch wall that makes the floor area an inclosed area? That is OK, some new construction homes are doing away with the dam.
What you might consider is finding a strip of chrome metal that is about one inch wide and 1/16 inch thick and silicon caulk this on the tile floor to act as a threshold if you will. If allowed to dry, the silicon under this strip will seal properly and seat it also. But, if you wanted to take another step when you decide that you will use this system, then insert plastic inserts into a predrilled hole and srew with flat head screws this down with three screws.
Now, the sweep on the bottom of the shower door will have a smooth surface to squeggie down to and make a seal. with the rubber squeggie, have it slanted slightly toward the inside of the stall as to create an angle that will shed the water down and away from this threshold.
I think that this will work for you and while you ponder the decision, your idea with siliconing the grout gutters where the rubber squeggie is hitting will also stop the water.