Just beacuse they can does not mean it is good for them
I could pull you up a nasty thread with a kid that slowly acclimated his SA cichlids to brakish water, and at the same time acclimated some damsels to brakish as well. Then, he put them all in the same brakish tank. Several types of fish that were not meant to live in brakish, but there he did it. It was not responsible, and he had no care for the needs of the fish.
Mollies are different, they can be brakish, but I would not keep them in normal saline ocean water.
-Diana