This rule comes due to several near tragedies and one fatality where sailors are trapped under a capsized boat. Ref: http://www.sail-world.com/index.cfm?Nid=5931
What ISAF wants is a system where you can release the bar/hook from the harness easy if you are trapped. I think Neil Pryde has a quick release system (that wears over time, and suddenly drops you into the drink, my experience from windsurfers). Ref: http://www.neilpryde.com/en/2005/equip/equip_product.php?ID=10
(did not find any quick release on your store Mary, but you did have the Bethwaite system that also should have been allowed)