How do we know if this is a legitimate DoD source code repository?

Why is this site hosted on a non-.mil website? I would like to use these containers for Department of Defense develpoment, however I have no assurances that this domain: dsop.io is a legitimate one. The SSL certificiate lacks information and is used by the free Let's Encrypt SSL provider, and the domain whois registry is anonymous for the domain dsop.io. Can you explain why this is not hosted on a .gov or .mil domain?

WHOIS search results Domain Name: dsop.io Registry Domain ID: D503300000853933506-LRMS Registrar WHOIS Server: whois.godaddy.com Registrar URL: http://www.godaddy.com Updated Date: 2019-04-10T20:43:32Z Creation Date: 2019-04-10T20:43:30Z Registrar Registration Expiration Date: 2020-04-10T20:43:30Z Registrar: GoDaddy.com, LLC Registrar IANA ID: 146 Registrar Abuse Contact Email: abuse@godaddy.com Registrar Abuse Contact Phone: +1.4806242505 Domain Status: ok http://www.icann.org/epp#ok Registry Registrant ID: CR367455303 Registrant Name: Registration Private Registrant Organization: Domains By Proxy, LLC Registrant Street: DomainsByProxy.com Registrant Street: 14455 N. Hayden Road Registrant City: Scottsdale Registrant State/Province: Arizona Registrant Postal Code: 85260 Registrant Country: US Registrant Phone: +1.4806242599 Registrant Phone Ext: Registrant Fax: +1.4806242598 Registrant Fax Ext: Registrant Email: dsop.io@domainsbyproxy.com Registry Admin ID: CR367455307 Admin Name: Registration Private Admin Organization: Domains By Proxy, LLC Admin Street: DomainsByProxy.com Admin Street: 14455 N. Hayden Road Admin City: Scottsdale Admin State/Province: Arizona Admin Postal Code: 85260 Admin Country: US Admin Phone: +1.4806242599 Admin Phone Ext: Admin Fax: +1.4806242598 Admin Fax Ext: Admin Email: dsop.io@domainsbyproxy.com Registry Tech ID: CR367455305 Tech Name: Registration Private Tech Organization: Domains By Proxy, LLC Tech Street: DomainsByProxy.com Tech Street: 14455 N. Hayden Road Tech City: Scottsdale Tech State/Province: Arizona Tech Postal Code: 85260 Tech Country: US Tech Phone: +1.4806242599 Tech Phone Ext: Tech Fax: +1.4806242598 Tech Fax Ext: Tech Email: dsop.io@domainsbyproxy.com Name Server: NS-223.AWSDNS-27.COM Name Server: NS-880.AWSDNS-46.NET Name Server: NS-2042.AWSDNS-63.CO.UK Name Server: NS-1492.AWSDNS-58.ORG DNSSEC: unsigned URL of the ICANN WHOIS Data Problem Reporting System: http://wdprs.internic.net/