Except this particular piece is quoting a large number of high profile investors who probably do have corresponding short positions against the market. There's hardly any author commentary in the piece.
Unless he asked 50 investors of which only those 19 responded with negative indicators and the rest were neutral/positive.
Well yes, though the OP was referring more to those making the statements not having skin in the game, not a general consensus of the market. If you asked 50 investors their views on the market a month before the '08 crash, I am guessing only a small fraction of them would have responded with negative indicators as well.
I think he asked "what scares you", because he thought it would be clever to do just before Halloween. So all the responses are negative, because that's what he asked.