I agree that US Air's behavior appears outrageous based on the OP.

(I don't really understand how a previous poster is unable to distinguish between one time denial of access to a club and permanently revoking something that the OP paid good money for.)

However, I can imagine one thing that US Air might suspect happened. Suppose OP appears to be a young man in his 20s and has recently begun presenting a long dormant lifetime membership card. Could the club be concerned that really belongs to his same-name father rather than him? That would explain why US Air thought there's no way the OP could have a lifetime membership.