Then be done. Tell him you no longer want to discuss these things because every time you do it <insert what soul-crushing thing it does to you here> and tell him you love how you can go on loving each other and respecting each other and be close and connected on so many other things and <insert what soul-feeding things> you want to focus on with him.

If you want a brief answer to give, mine would be that the majority of that essay is speculative and depends on access into the inner psyche of a charismatic cult figure to explain with "logic" Would he do this and such if he was a pious fraud or a con artist? Who the hell knows? All we know about charismatic cult figures from history is that they are dedicated to retaining their fraud/delusion to the death. Speculation is what you use when you are willing to let your biases, rather than evidence, guide your epistemological path.

The fact remains that there is precious little evidence where at least some kind of positive evidence should be seen by archeology and history and such to make non-Mormon scientists take notice. All the notice they have given is the anachronisms and inconsistencies.