We supposedly live in a secular democracy.
The point (at least one point) of medicalizing suicide is to adhere to Judeo-Christian values without actually saying we are.
According to many versions of Christianity, those who engage in suicide may go to Hell, or at least not in Heaven.
Suicide prohibitions inherently enforce implicit theological beliefs that what ever happens after death for those engaging in suicide is always worse than any current or future on Earth.
If we want to actually live in a secular democracy then suicide needs to be respected as a civil and human right for all adults when it is done in private.