plenty of fighters take fights with debutants. Kovalev's first fight against a debutant. Pongsaklek fought three debutants in a row after his draw with Naito. Chavez fought 10 debutants early in his career. Nobody says "well their records are actually (whatever original record is minus debutants). Floyd actually fought two debutants in his career and I never heard you challenge 49-0 so far.
Saying that this wouldn't count for Floyd then not criticizing others who fight Debutants (not even getting into fighters who face opponents with badly losing records) is pretty openly hypocritical. Nobody would be impressed by Floyds' win over McGregor, but he'd be 50-0, no question.
Basically, no matter how you spin it, Floyd would be 50-0. Wouldn't be that much more impressive than 49-0, but nothing you do will take that away from him unless you're willing to reduce the numbers of a LOT of fighters. Now stop being a whiny bitch, you're not even arguing anything.