a couple of points:
because of the change to net pool pricing from standard pool pricing when the article was written the bettor gains. in Beyer's article the other 2 horses only paid $2.10 when the big horse showed. Bellafina created a minus pool at Santa Anita on 2/9, she showed and the other 2 horses paid $2.40 and $3.20 because of net pool pricing.
But the more interesting point is that Beyer is actually wrong. You can't guarantee a win because if 2 horses are longshots in the show pool and they don't come in you may not have a profit.