No, the fresh water always produces less energy than it took to desalinate the fresh water to begin with. If the freshwater is recoverable, that will always be energetically better. But if you can't recover the fresh water for some reason, like say there is a particular contaminant that is impractical to remove, or it's going to be used for some application like irrigation or feeding a nature preserve where higher salinity is tolerable but you're never getting the water back, then it reduces the overall system losses.
On the other hand, there are often restrictions on how concentrated your brine can be when released so it doesn't cause environmental problems. If you have to dilute your brine anyways, might as well get a little energy back.