"Security. Naismith's cover depends on my clone story. This clone story would muddy those waters considerably, if it got out, which it inevitably would. Better to just slap a lid on the whole thing and thereby keep control of exactly what mixture of truth and lies becomes attached to Mark's official public existence, if he gets one. Not to mention avoiding the enormous publicity we'd inevitably get if the police and the news media started digging into this whole sordid business."