i think it also highlights the modern aspect of the manga's setting - where human rights for omegas exist. I don't think it is out of place - rather it's a beautiful way to remind us of the time zone [that was mentioned from the start]
MAKE SURE YOU SUE HIS ASS AND RUIN HIM LAWYER-KUN
I didnt think it was out of place... but it felt more of a slight after thought. Like I was thinking she would've gotten advice from him how to be a more powerful or commanding person as an Omega.... and maybe he would be the one to suggest a lawsuit, rather than her outright suggesting it. Even in Law and Order shows, victims are reluctant to face their abuser.
I feel like the last extra turned so... meta. The assault charge seemed kinda random to pop up... but considering a side story with Sei and his bf was about an Alpha getting sex charges on him for attacking his omega friend he wanted to be paired with, it makes sense.