You are partially reading it wrong. Yes, they use the shorter arm but the article clearly states it is a rubber bushing.I guess I'm reading the article wrong or something. It seems like the article is recommending a shorter third link with a poly bushing,
"The Roush 3rd link has a small, hard durometer rubber bushing that dampens the shock from the rear-end and greatly increases rear grip over a spherical or polyurethane bushing."
I also want to know why they opted to use the shorter/older version. And, how they will adjust pinion angle if they have to.