Are you really trying to say that any LTC who gives YOU a line check must have more than 15,000 hours? If so, that is a fantastic theory.
A line check should simply be to ensure that the flight is conducted in a safe and professional manner and within and in accordance with the company SOPs. How many hours the LTC has in his or her logbook is irrelevant.
If you feel that you have been unfairly treated then have no hesitation in contacting your Chief Pilot.