Just personally I think this is the disconnect, just because something is nofollow does not mean it does not help rankings in an indirect way....
"Google probably still likes to see that you are active and people are talking about you on the web"
Not sure this is a "probably" i think they have come out and said it on many occasions
And this I believe is the point of YES they help, the Algorithm is becoming less and less robotic.... so thinking of it in a sense of Follow and Nofollow is not looking at it in the full perspective.
I also think #2 is not looking at the big picture of, are you in a niche that you could gain more traction from Social than in search?
I am just not sure an SEO answer is correct in an increasingly social world IMHO
So if we are looking at in perspective of what to do on 12/13/12 - #2 might be correct for some niches, but for 12/13/13 and beyond I think #2 and #3 will keep getting more and more wrong.... Not just from a search perspective, but from an Internet Marketing/Marketing perspective as well.
Just be creative as your competition obviously is not