Hi, BT, whilst it is good of you to have such a requirement to log in, I am sure you will know that it is not an absolute solution to prevent adverse and wilful comments against you.
This is because any wilful person(s) will post adverse comments against you on other blogs, given the wide network of social media networks. You mentioned "taking them to court", but it is a very tedious process. Firstly, you have to track and identify the true identity of the person who made the wilful comments. As you know, there are many ways to avoid detection. Secondly, you have to serve the legal documents before a court hearing can take place. All these cost money. Thirdly, assuming you are able to accommplish the above 2 conditions and you are even able to get a favourable judgment, there might also be problem.
Our legal system is such that the loser will pay compensation and legal costs. What if, for example, the loser refuse, or cannot affort, to pay? You will end up having to pay your own legal bills and also take further action against him. To put it bluntly, you will be forced to make decision to throw good money after bad. Which is why we don't see many legal actions of this sort.
SunnyGale commented that you are using the LKY tactic. In those cases which the late LKY had sued, the defendants made those comments publicly, and so it was more straightforward for him. In any event, the late LKY has all the resources needed.
Your blog already has a reservation that you have the right to censor and reject wilful posts. That should be enough.
So, my thoughts are these:-
1. Might as well let those wilful posters continue if they still need a false sense of superiority complex. Most of your readers are mature enough to know what is right and what is wrong.
2. By imposing restriction(s), it might give him the misguided interpretation that he had succeeded in annoying you.