For the record, I consider myself an authoritarian progressive, but I don't square with a lot of modern progressive ideals concerning identity politics and multiculturalism. I'm a staunch nationalist who believes that the ideal of the melting pot requires immigrants and minorities to assimilate into mainstream society and to consider themselves Americans first and foremost. The modern movement has lost sight of the ideals of President Theodore Roosevelt.
And the problem with Rand's fiction is that all of it is written in support of her intended moral, so of course the plot resolves in such fashion to "prove" it.
The moral of the Wynand story, as I understand it, is that failing to recognize the source and nature of your power means risking the misuse and sudden failure of that power. Everyone should know and understand the source of their power, and the limits of it, in order to exercise and develop it prudently. The fact that so many people fail at this is what provides opportunities for upstarts and rogues.
Moral authority is a very sticky source of power, because while it gives you tremendous influence over the thoughts and actions of others, that power is conditional upon their recognition of your moral authority-- which means that you cannot contradict the moral values they have imbued you with. Major changes in ideology or goals must be approached slowly and carefully.
On the other hand, moral authority is the best kind of power to wield... because if you are attacked, even people who do not accept your authority directly will spring to your defense. It is the safest and most enduring form of power that a human being can wield, as long as they acknowledge its limits.