The team is a mix of employees and contractors. They also offer customers (government agencies who use their service) the option to use Bing results or their in-house Elasticsearch results: https://search.gov/admin-center/content/content-overview.htm...
They do good work, and it’s an important service. I believe it saves a ton of money for the federal government by reducing reinvention of the wheel. As a former federal employee and current federal contractor, it’s been very helpful to be able to use their no-cost-to-customer search services on multiple projects. On my current project we eventually shifted to doing our own search (using Postgres full text search) so we could customize the indexing and ranking, but Search.gov was a useful interim solution.