I work for a contractor and we developed the site – and we did not have to deal with the security clearances.
We are in the process of migrating it to a SAMHSA.gov. url.SAMHSA does own it, but we are currently managing the site
As for choosing Kentico – I am not on the technical team – but I know that our team did compare several content managment systems and felt that Kentico best met our needs – we are also using the platform for an web-based toolkit for Behavioral Health Recruitment and Retention – so we chose Kentico because it could fufill several of our needs.
Although there is a ‘public’ part of BHTalk – most of the ‘fun’ happens in the groups, most of which are ‘closed’ groups of grantees.