Regardless of what the Rambam said or didn’t way, WE can not posken according to the Rambam. WE posken based on what OUR Gedolim say (having learned the relevant sources and understanding them much better than we can and knowing how they apply to contemporary society).
Rav Moshe Feinstein Zatsal has very strong words to say regarding someone who DOESN’T learn because he doesn’t want to take money. I believe that someone may have quoted the source earlier (either in this thread or another one). If not, I would appreciate it if someone who knows it could bring it (I don’t have an Igros Moshe handy).