Seems like we could also just add it to the other places where water is flowing into the ocean. Do we not disrupt the ocean ecosystem with our fresh water runoff?
But... If you are using this water for drinking, it's going to come back through the sewage system, and maybe you can dilute the brine with outflows from local sewage treatment plants.
Depending on details, the combined outflow could be more or less salty than the seawater input to the desal plant.
Also, a lot of places are using desal to augment other supplies. If you've got 15% of your municipal water supply coming from desal, sewage treatment outflows should be significant compared to brine.