There is no keel stub, and there are no keel bolts. The lead was cast as one piece and then lowered into the fiberglass cavity. The hull would have to come apart for the keel to get loose. That being said, I really don't know what what the problem shown in your photo might be. Sorry!
The hull IS coming apart; that's why I suggested either having it re-surveyed by someone who KNOWS WTF they are looking at or go back to the surveyor and ask for a second look or possibly put a claim in (but clearly not an option since it was an insurance survey). We know how the hull/keel is constructed; the question was about the LARGE CRACK running along the turn of the bilge at the keel stub (in a high load area).
I did not know that the survey was an after-thought to get insurance. It's possible that the surveyor was trying to do the owner a favor by not saying the problem is more significant in his report to allow the boat owner to obtain insurance; but I don't know what he was thinking or exactly what the problem looks like either.
To me, this longtudinal crack looks rather large; and scary. Is it just the picture or is the crack over 1/4" wide and ~6-8" long at the top? At the least I would think the area should be ground back to good glass and then layers of glass and epoxy filled in to the void; with a few layers of cloth over the top to aid in load distribution. But again, this is pure speculation; I'm not able to look directly at the problem.