If laurel seeding around your area is a concern......as it is where I live......then yes. Otherwise not really necessary

we are in DC area and never deadhead ours.

The garden center employee related that those flowers do not seed.

Sorry but the garden center employee is wrong. "When the flowers fade, small fruits aren't far behind. The "cherry" in "cherry laurel" is a true description because Skip Laurel is in the same genus as edible cherry trees. In fact, Skip Laurel does produce cherry fruits, but they're not what you may imagine. Instead of the bright-red fruits that you enjoy eating, Skip Laurel bears purplish-black cherries. Although you won't find them appetizing, your backyard birds will thank you! Many bird species relish these cherries, such as robins, cedar waxwings, and bluebirds. When you're considering what type of plant to purchase for an evergreen hedge, plant Skip Laurel and you'll also be growing a food source that feeds the birds!"

The plant itself has no need to be dead headed, if that is what you were asking. And what a chore this would be!