I think the rule is, based on the above testimony, NEVER EVER DISCLOSE YOUR AGE ON AN APP. Only say you are over 18 -- if they require more than that, tell others and contact your lawyer, and prepare to participate in a class action suit. But do not disclose your age because the law specifically states that you don't have to, and by doing so, you can make it more difficult for people to make hiring decisions without taking your age into account.
I just read in my HR text that the status of age discrimination legislation is "uncertain" because there are questions over how to apply it (GEEZ HOW ABOUT CONSCIOUSLY EXCLUDE AGE FROM THE LIST OF REASONS TO HIRE?). This is a sign that business professionals, as a group, are moving in direct defiance of the law.