[1] http://postmasculine.com/the-fake-alpha-males/comment-page-1
These are two different people and its all about where the person is coming from. If a person is putting themselves into a position to fail they are considered strong because they can afford to fail, the thought being that they obviously have a lot of confidence and competence in some other parts of their life.
If a person is weak or obviously trying to appear tougher than they really are, we say they are vulnerable because we know they are compensating for something.
All of this is to say that boldly putting yourself out in the world for criticism is a powerful thing to do because you are obviously secure enough to accept some criticism. The solution proposed from Manson appears to suggest that if you are vulnerable that you are powerful right now, but that isn't true.
This basically means that you need to be powerful to let yourself be vulnerable, otherwise you aren't letting yourself be vulnerable, you are being forced to be vulnerable. So the issue for weak people remains in TRP as well as in Manson's case, how do weak people become powerful?
Now I don't mean to spin all this around about the book, so I'd suggest reading through his blog posts, perhaps starting with the "best articles" to get an impression of what he's about. I'm positive that someone open minded enough will get something compelling out of it.
One other interesting point is the possibility that making oneself vulnerable is a proxy for risk taking which is a more masculine tendency.