There are many potential benefits the SIAI could gain from an affiliation with those inside the higher status AGI communities. Knowing who to know has many uses unrelated to knowing what to know.

Does this suggest that founding a stealth AGI institute (to coordinate conferences, and communication between researchers) might be suited to oversee and influence potential undertakings that could lead to imminent high-risk situations?

By the way, I noticed from my server logs that the Institute for Defense Analyses seems to be reading LW. They visited my homepage, referred by my LW profile. So one should think about the consequences of discussing such matters in public, respectively not doing so.