Thanks Justin!
I just got a reply from Mike at YouTube Nonprofit ---
Mike confirmed that this is indeed a bug and he added that:
"You can't create an account if we detect your birth date was in the 19th century. :)"  He then suggested that I set up another account, which I had already done ... following your advice.
I simply changed the "birthday" to 1990 and had no problems setting up a channel.
So, I thank you again for your prescient advice.
Sincerely,
Gary ...