I expect his past statements on that subject would be far more reliable. Maybe we'll soon have a fairly complete picture of his beliefs in that regard.
To the best of my knowledge, his past statments are all scholarly works. The excerpts of law review that he wrote, that I've read, make no claim of "superiority" of sharia over other forms of law, which is the entire premise of the OP.
What The Media Is Not Telling You About The Muslim Who Attacked Donald Trump - Shoebat. This is where I saw the snippets of law review. They do not supprt Shoebat's conclusions either, the excerpts of the law review are clinical dissection of Sharia.