You are too logical in your thinking Grey.....that is what separates the bad folk from the good folk...ie: common sense.
No, if he's asking the why of a thing he is on the wrong track:
If you ever have to ask the why of a thing, then the answer is always "Money", "Power" or Both.
We don't have a Justice System, we have a Legal System. If this case were looked upon as cut and dried as it almost certainly is, how does that generate money for, or increase the power of the Lawyers and Judges that populate the system?
The domestic abuser in this case won't be able to pay a Lawyer ..... and his Public Defender won't be able to drag this out very long ...... where's the money in that? As for power, they already have him ......he's got nothing to lose, now. Mr. Kinney has a career, and home that he'll be willing to fork over pretty penny to keep ..... and may even lose his house to finance his defense .....
In a Justice System, the perp in this would be forced to pay his own medical bills, all court costs, reimburse the homeowner for the property damge and for his ammo spent stopping his home invasion, and at the end of it all, get a beating equal to the one he gave the woman. He ought to be happy he got out of this mess he made still being able to breathe at all.