I believe op can always ignore the messages totally but it doesn't make sense for this kind of thing to be happening for a reputable gambling platform. I know that many other sites do the same without minding your consent which is irrational to me.
I am not aware of the rule because I can control how I gamble I don't think I will go to the point that I will need to exclude myself from a casino, if I want to take a vacation I will just unsubscribe and will take a vacation from posting or reading any online materials that deals in gambling until I can deal with my gambling habit effectively.