Yes, it is interesting, but not surprising that Jehovahs Witnesses are not the only ones who can't quite wrap their head around the fact that the Law was not just a code of moral conduct; it was a civil and criminal code as well.
(e.g. Christians never seem to get tired of making fun of the excruciating level of detail that defined 'Work' on the Sabbath. But when a severe criminal penalty is involved, that level of detail becomes inevitable.)
Christianity was never a civil and criminal code; it came into existence at the height of the Pax Romana and left both high and low justice to the State. After the destruction of the Second Temple, Judaism started to evolve along similar lines.
In this particular example, (Deut 21:18-22) the idea that anyone regardless of whether they're Christian or Jew would seize judiciary power and impose penalties in the Law for criminal behavior is either stupidity or hyperbole that went entirely over my head