There is no problem as regards British citizens residing in Jersey; but purchase of a property is strictly limited by UK legislation to those who were born on the island, have lived there for at least 20 years, or are of very high net worth - the latter category is presumably that referred to in the article you read. As the law applies only when property is purchased, it is clearly fairly easy to police. Incidentally, Brussels doesn't really come into the picture, as the Channel Islands are outside the European Union.