Yes - having experimented a lot with our hooks on the piling at our mooring, I struggle to see how correctly used hooks on piling in good condition and near the bolts COULD come loose without a good amount of slack in the rope... but then I imagine there is a lot of variation in the hooks and the piling?
It isn't really unreasonable, and it's no big deal to just use chains instead so we will.
The people I spoke to at the insurer seemed unfamiliar with the hooks, pins and chains. I wondered if they were more used to coastal boats. Might be worth running the scaffold pole arrangement past yours...