Looks like a standing platform, some guys use them for spotting top water fish, it is similar to having a tower, but lower and without controls and the top. The bottom piece is support for standing since the stock hardtop would not be enough. The pins make it removal, so it can be taken off the boat when not needed, and more importantly, so that the boat can be trailered. It would not be a good spot for a life raft, too high up on a small boat, it will cause to to rock, in rough conditions it could get pretty bad. The hardtop was also not meant to support a liferaft up high, Grady hardtops on smaller boats have been known to crack when that much weight is added. Since this had a standing platform, I would check your hardtop mounts for loose supports and tighten all your fasteners, as well as your hardtop legs for cracks(the welds sometimes crack).
