With that definition any moral code can he universal.

I can support legalized murder and condemn everyone who doesn't, therefore creating the grounds to condemn anything else.

Some religions practice human sacrifice, including of children.[1]

My opinion is we're better off arguing there's a better moral code based on a number of arbitrary parameters (freedom, resource creation, comfort, longevity, equality, merit, envy management, violence management, respect for tradition, respect of minorities, etc). I can't see how you can declare a universal code of conduct, I can see how you can declare a technocratic liberal one.

[1] https://en.m.wikipedia.org/wiki/Human_sacrifice_in_Aztec_cul...