ampm, es lo que pasa cuando pides opiniones: todo el mundo tiene derecho a opinar.
Si lo que quieres es una respuesta de autoridad, pues tu mismo la has linkado. En el articulo de Sergio Blanco hay un enlace a una entrevista a Matt Cuts, ingeniero de google (que supongo que sabra algo de como funciona google), donde la parte que te interesa es:
Cita: (Matt's precise words were: The nofollow attribute is just a mechanism that gives webmasters the ability to modify PageRank flow at link-level granularity. Plenty of other mechanisms would also work (e.g. a link through a page that is robot.txt'ed out), but nofollow on individual links is simpler for some folks to use. There's no stigma to using nofollow, even on your own internal links; for Google, nofollow'ed links are dropped out of our link graph; we don't even use such links for discovery. By the way, the nofollow meta tag does that same thing, but at a page level.)
Es decir, que le da lo mismo que uses nofollow que robots.txt.