The vast majority of products simply do not cater to every demographic. Racism might at least be reasonably considered inappropriate unless you're marketing a product that specifically targets some races and not others, but ageism? It's highly likely that whatever it is you're advertising does have a well-defined audience in terms of age.
This is just another rung on the political correctness ladder. Expecting everyone to include every possible demographic in every conceivable advertising campaign is idiotic.
Making it about "what people want to be" (from GP) misses the point as well. If you're not aiming your advertising at your target demographics, you are failing either yourself or your client. That's not discrimination; it's business. Discrimination is "you're not pretty, you don't get a discount or aren't allowed to use this service."