I don't believe a keel/hull joint should move. The surfaces of the keel top and mating surface should be a perfect match. Many builders use epoxy putty of some type to fill in any gaps when the keel is attached. Builders like Hinckley will work hard to make the 2 surfaces a perfect match by planing the lead until it is perfect. Then a layer of sealant is applied most of which will squeeze out as the nuts are tightened. But they are a rarity. Once the keel bolts are torqued properly there should not be any movement. If it moves a little, over time it will get worse. But I don't think a proper job can be done without dropping the keel. Sealant is designed to keep out water but not to fill gaps that shouldn't be there.
Living aboard in Victoria Harbour