I was told by the tech that set us up that you really shouldn't grease the "L" pin surfaces, as that is where the anti sway comes from.
The sway mitigation in this hitch is mostly at the head, not the L brackets. The L brackets, if lubricated, will operate in a slightly less efficient manner. Progress Mfg, the makers of the hitch, recommends lubricating the sockets where they come in contact with the head. That has little or no affect on how the hitch works. Lubricating the ends of the bars into the sockets will also have no affect on how the hitch works. Putting grease on the L brackets where the bars contact under tension would have some affect on the performance of the hitch and some noise is probably a better choice than any loss of performance. Noise is part and parcel of the hitch and if it gets to be bothersome, there are quieter hitches.