The thing is with splashes is that they keep getting lighter with each new generation, to the point that they may appear white or a silvery white with little streaks of pale blue infused throughout. I have a couple of birds that in two generations had gotten this way. What your breeder is probably suggesting is that in order to keep your splashes from appearing too white, you should breed blues to your splashes, because breeding splash to splash will lighten the color too much.