It's pretty arrogant, though. The LDS think the true church disappeared after the death of the last apostle. Do they seriously think that Mary, of all people, wasn't already baptized by then?
This sort of thing only makes sense if the LDS really believe that the true church never existed on earth until Joseph Smith.
It is not only arrogant, it is also questioning God’s character and ability.
They would have to make the claim that didn’t know what he was doing when Christ walked the earth.