"Rationalization" is being used as equivalent to sophistry.
We're talking about objectively defensible and demonstrable reason, which is another thing altogether.
Reason demands that a moral code (a system defining good and evil among humankind) applies to all humans equally.
If it does not, then it fails the first test, and is hence irrational. (whether some clown "rationalizes" it, or not)
Imposing morality, that is.