I think the author is fuzzy on the concept of “a third”. which implies 3 equal parts. There is no way that 1/3 of the current Jewish population in the United States is conservative. I also think he overestimates the moderates and underestimates the progressives, but I could be wrong there.
That said, there are some magnificent Jewish conservatives out there.
There's me, but I'm not so sure I am magnificent.