As near as I can make out, you are arguing that a subversive work is one in which characters above the lowest possible social class are not all paragons of perfection. I do not think this is a useful way to use the word "subversive."

Why oh why are you saying "So much for kings"? Is Tolkien subverting the institution of kingship? Hardly. Kings are just fine in Tolkien's eyes and I don't see anything in the book that can be read as an objection to them -- except that they aren't perfect, and if that's your standard, there's no form of government that will please you.