Might someone have been going to install the remainder of the
installation: the connection to the
hull, (which would have been reinforced.) It is one of the problems to installing unplanned by the
designer inner forestays, that you have to figure out how to take out the loads, and make it so that the inner stay's loads don't pull the
deck up.
As it sits, it is useless. But if you look at the above decks part, it looks to me as if something may have screwed down onto it at one time.
Some of the Island Packets have a fitting for a boom for a staysail in a similar place....
Ann