The NSA, the original primary developer of SELinux, released the first version to the open source development community under the GNU GPL on December 22, 2000.[6] The software was merged into the mainline Linux kernel 2.6.0-test3, released on 8 August 2003. Other significant contributors include Red Hat, Network Associates, Secure Computing Corporation, Tresys Technology, and Trusted Computer Solutions.
Though this implies that the Department of Defense doesn’t want to use compromised tools, since DARPA is DoD. NSA is also DoD.
They wouldn’t want to use or derive any compromised software themselves. They would want any adversaries to have it implemented.