The logic of his statement doesn't stand up however.
Prohibition laws regarding popular and easily obtainable narcotics do not reduce other crimes, but rather, in several measurable ways increases them, the most obvious one being that it then directly finances a lot of other organised crime.
Police logic doesn't always stand up. They know what makes their job (catching bad guys, getting convictions) easier, not what stops crime at the source.
Prohibition laws regarding popular and easily obtainable narcotics do not reduce other crimes, but rather, in several measurable ways increases them, the most obvious one being that it then directly finances a lot of other organised crime.