John MacArthur has a lot of Masons in his genealogy. All of G.K. Chesterton's forebears were Protestants of different types or Unitarians. Yet Chesterton was one of the preeminent apologists for the Catholic faith in the first half of the last century. Charles Darwin had a thoroughly Christian heritage yet his theory of evolution contradicts the Bible, and only Marx is greater than Darwin in the atheist hall of heroes.
Judge MacArthur or any other man by his works and deeds and not those of his ancestors.
Everything you state seems reasonable.
But my point is I think there’s a good chance John McArthur himself is a Freemason.