Probably MOND is a "good enough first approximation" to the whole story, which might come out later, and include more terms. I think it's interesting some people are doing the complex (to me, anyway) maths from a theory point of view to find ways to get it to spit out MOND. I have almost zero understanding of all this, but none of the theories I read seem physically insightful. They say MOND a_0 constant is close to cH_0, but not exact. I wonder if some of the difference (if that is significant) could be c altering.