13-year-old boy sentenced to jail after saving mother from rapist: why?

Judgement at times is never fair;
Should one allow a wrong to be
Committed because the world will
Never understand; what if that wrong
Is being committed against your mother...
Would you not stop it by any means
Neccessary? And only worry about the
World after your loved one is safe. A
Wrong is a wrong and will always be
A wrong, this is for the rapist who
Caused pain, and did not care about the 
Consequences until action was taken
By a 13-year-old boy who if it were up
To him, on that fateful day, would have
Rather been a 13-year-old boy and not
A protector and saviour.