Autolykos,
I’m not sure where the disconnect is. The murderer is not respecting you as one who should actively seek happiness, therefore he is not actively seeking happiness in a way that respects another as one who should seek happiness, and his “happiness” cannot be defined in a non-distorted or uncompromised way. Also, since you respect yourself as one who should actively seek happiness, you can defend and secure your property, body, and authority from interventions which are against your consent. One of the goals of justice, defense, and forgiveness is to restore clarity in our relations of body, property, and authority. The ideal social-systemic condition involves collective individuation free from illegitimate disturbance.
https://forum.freecapitalists.org/t/illegitimate-disturbance-a-brief-introduction/18716
I think what you’re getting at in a way, in everyday language, is that even the criminal has certain rights, that it’s wrong to use excessive force, etc.