They were sealed because the abused woman refused to cooperate with the state - a pretty common occurrence with abuse victims and definitely not “proof” that the initial arrest should be hidden from public view.

Everything in the initial report is pretty horrible.

Defamation requires the information to be false.

As a blanket statement that is incorrect. For example, in Finland it doesn't have to be false.

Possibly true, but not relevant to a case in California.

In the US the truth is an absolute defense for liable and defamation (aiui)

This is a good point. In a similarly salient vein it is legal to drive without a seat belt in New Hampshire and federally illegal to catch lobsters below a certain size in the US.

If they were sealed, it stands to reason as well that the journalist may not have seen all the sealed records, leading to an incomplete picture. Perhaps the girlfriend had a written recantation, or came to a mutual understanding, or a psychological assessment was conducted, or it was discovered she was the instigator; we wouldn’t know, it’s sealed. Good luck defending your name publicly when your defense requires pointing to sealed records the public can’t verify.