The client seed isn't something that needs to be kept hidden from either party. As soon as you set it, the casino knows what it is.
Getting the "secret" on your side known by the house can let them doing any manipulation, drawing any result they want
in example if they detect you playing auto-bet will let them know the bets that will be placed
There is no secret on your side. When you set your seed, they know what it is right away - they use it to determine the outcome. They have to set their seed first though, which is what prevents them from making any changes after you set yours.