Educate me on why Larry Holmes didn't unify with the WBA.

I was around then too and have to agree. I don't think failing to fight Greg Page or Pinklon Thomas means that he would have necessarily lost either fight or that a win over either would have added much to his legacy. Besides even after he got old, Holmes still showed flashes of brilliance beating the likes of super underrated Ray Mercer and showing some heart in an admittedly short fight against Mike Tyson. Holmes was also one of the final greats of the 15 round era, which distinguishes him from many of his modern 12 round peers.

Holmes embarrassed a completely shot Ali. I can still recall the huge amount of racial tension as associated with the Cooney fight. I believe that both fights unfortunately really hurt his legacy in the long run.