It won't work. Because Gomi strangled Moyupu. Strangling takes time and needs a lot of force. It can be easily proved as unnecessary force. Funny thing - additional stabbings won't work against them because criminologists can find the time of trauma appearing but not too precise.
Well, this is debatable coz Japanese laws about self-defense are pretty tough (as chatgpt says). If Moyupu had relatives they would want the maximum punishment for Gomi.
Are you sure? Gomi is into pretty heavy stuff like raping underages. That's not normal at all.
Also Yumezora behavior could be questionable in the future. What if she will be bored? What if Gomi won't be able to satisfy her sexual urges?