Learning Rambam is not claiming he had absolute truth.
It is searching to truth and justice. The Rambam posits a system of a priori values that the mitzvas are to bring to. [The Sefer Hachinuch brings them on each commandment] Certainly you will admit that is already an improvement on judicial activism of Supreme Court judges that think that if they say something that makes it moral and obligatory for people to listen to them.
But there are books on a secondary level that are needed to find the depth of the first level books--for instance Aristotle I think is necessary to understand Plato. Some later people are important to understand Kant.
So an author like Reb Chayim HaLevi is important to understand the depth of a first level person like Maimonides. For example most people open up a Rambam and don’t see any problem at all. (They never get past the superficial level.)