In my experience, use of a good sealant makes brake dust wash off easily with regular car soap and use of a sponge/brush/wash mitt but does not make brake dust rinse off with just a spray of water.
This is based on using the following products to seal my wheels: Klasse AIO/SG, Sonus AG, Duragloss AW, and Werkstatt Prime Strong. All of these work well but none of them have enabled brake dust to rinse off just by spraying the wheels with water.