That'll be why the damp specialist doesn't want to lift the boards then. If it all goes tits up and a screw goes through a pipe/cable when they're put back that's one bunfight that no-one wants to be involved in.
Be interested to see what comes of it. Unless being able to poke about was a condition of the offer or they’ve already exchanged it’s very good of them to let it go ahead. Or a little naive.
They have permission from home owner to lift boards?