Have carefully checked the Constitution here in the United States... nowhere does it say "except for airline revenue pilots" when listing rights and freedoms.
Age is not a protected class. Age limits are legal, provided they meet the criteria set up by the Supreme Court. Rights are not unlimited.
I can't join the military at my age, there's an age limit on running for president and being a firefighter and lots of other things. When Hollywood casts a love story about college kids they can turn down a seventy-year-old actor. Nothing magical about age - not legally, anyway.