Just recently, it was posted on the DEF CON website (https://www.defcon.org/) that they are requesting that the "feds" do not attend this year's event. Although there is no concrete indication as to the reason for this request, it has made us reconsider our opportunity to present at the event.
We do not want to make this a "political" move, and we do not make this decision based on their motivations. The issue we are struggling with, and the basis of our decision, is that we feel strongly that DEF CON has always presented a neutral ground that encouraged open communication among the community, despite the industry background and diversity of motives to attend. We believe the exclusion of the "feds" this year does the exact opposite at a critical time.
The SharePoint talk is already scheduled to be presented in an updated form later this year, so people will still be able to see it. We will also still release the tools and guidelines we planned.