If you scream at the top of your voice in a Church for fun it’s an offensive and probably breaks some kind of civil law.
If you make the same disruption because of a gallstone it’s not your fault. You need medical attention and probably a stay in hospital.
If you make the same disruption because of schizophrenia it’s not your fault. You may need medical attention and possibly a stay in hospital.
The brain is an organ of the body. The mind is an emergent property of the body.
An unwell mind or damaged brain is no different from an unwell gall bladder or a broken arm.
Circumstances are considered in proportion to the seriousness of offence. If you scream because of the stomach pain and happen to break the noise regulation law that will be taken into consideration. Like a cop may pardon you for a minor non-repetitive offence.
If you harm property or even people that is an entirely different proportion. Such thing should be dealt with and prevented in future regardless whether it is related to mental health or not.
And no, in this case brain is not equal to other organs as it directly controls the person’s actions. Your broken leg cannot intrinsically harm other people. Abnormal brain function can.