Every business should continually adapt to meet the needs of its customers. If there are people doing this then the airlines should recognize the demand and reach out to allow them lounge access without the need for pretend flying. Monetize it with some allowance depending on tier status, followed by a charge for any subsequent visit. Going after the most loyal customers and dispatching "corporate security" squads to investigate every fraudulently consumed donut doesn't seem very much like a businesslike response.