Law doesn’t work that way. In court, you can’t say “I did it because I was told it was ok.” That will land you in jail.
The only way they can avoid liability is by retracting.
Libel, which is civil, kind of does work that way.
Slander of public people had to be “malicious” to be actionable.
If a reporter can have plausible deniability, the reporter wins.