The site is "for people building, administering, managing and cultivating digital communities." Part of building and cultivating a community includes how to grow and develop the community, but this raises a relatively difficult to define boundary. At what point is a question purely about running a site or business and no longer about community development.
Arguably, just about anything can be related to trying to develop a community. When someone is making a new product, they are, in essence, creating a community of users of that product. I don't think anyone thinks that questions about product design (say building a jet fighter) should be on topic here, but it is indirectly related to what people will be fans of it and form a community around it.
This question presents a more ambiguous case. The question is about recruiting a third party poster to a blog, which has a community associated with the comments and those who follow the blog. On the one hand, having more points of view does increase the desirability of the blog and will likely draw more people in to the site, and thus the community discussing the posts, but it also primarily developing a content distribution platform rather than a community. The community is a secondary entity connected with the content distribution platform.
Is this really related to community building? How do we define the line more clearly between what is and is not community building versus what is developing a product that happens to increase the potential size of the community?