From the title of the orginial post, I thought it would be a discussion about shaving a drip rail.
Skinned a roof once. Actually twice. Once on my car and the second time on the donor car. Shaved the drip rails while I was at it. A ton of spot welds. In some places, several layers pinched together. If the roof has worm holes in it, drill the spot welds and cut the area out, make a patch, and weld it in like any repair. If the drip rail is rotten, that's another store. The roof needs to be out of the way to repair the drip. Just bending it out of the way is not really an option. The drip rail is part of the inner roof structure. There could be rot for several inches with no way to assess it. There was no sealing, coating, or paint in that seam area and it is a great area to catch moisture and mouse piss. If the damage is confined to the rail, I would consider repair of the rail. Afer the repair, I would roll the car upside down and inject some kind of rust catalyst around the entire roof seal perimeter.