"I thought she was not a child" is never a defense for raping a child.

Legally, no, you are right.

When third parties are discussing the crime, "the person who committed the crime may not have known they were committing a crime" is a valid, reasonable thing for a person to say as part of a discussion.

Doing so is not a defense of the person who trafficked the child to be raped.

You really do have a hard time responding to what people actually said.