The biggest problem is your friend is reading something written to a people 4,000 years ago as if it were written to him today.
It is completely ripping it from its context and the culture of the time.
For example, In the 1800’s, american teachers were allowed one night a week for courting, a second night if they attended church regularly. If I gave a new law at that time saying, date anytime anywhere, the culture would reject it. Likewise, if a neighboring culture practiced that, they’d likely be destroyed for their evil suggestion.
And today we look at such things as silly, even though they were essential then.
Another case might be in 1800’s America you were hanged for stealing a horse. This was the predominate cultural belief. If someone came and said, horse thieves should just do 30 days in jail, then no one would accept it and it would be completely rejected and no mercy would come to horse thieves. But perhaps the people would have accepted life in prison for the horse thief. Today it would look barbaric, but at the time, very merciful.
This same idea is in play in Hebrew times. At that time people raped and murdered each other for mundane reasons, they acted barbaric in many cultures at the time.
So God gave them laws and rules that gave justice despite their harshness by today’s standards. Even the idea of due process in the Old Testament law was something no one else received.
So it would be helpful for your friend to try and understand human culture at that time, and then study the Old Testament law, he will see how it is a refreshing change compared to how the rest of the world operated at that time.