MITRE is a non-profit company that operates Federally Funded Research and Development Centers (FFRDCs), which are owned and funded by the federal government and contracted out to companies like MITRE to operate them.

While MITRE does have contracts with DoD (and many other agencies across the federal government as part of the FFRDCs they operate), they are not the same as a stereotypical DoD contractor as their non-profit status motivates them to work in the public interest.

How is Go not general purpose?

Try to build a mobile app with Go.

How are you then defining general-purpose?

I'd say a language is general-purpose when it has not been tailored to a specific scenario or area of problems, but to work well for most. Isn't that, to a great extent, true for go?

You can build a mobile app in Go, for both Android and iOS.

https://godoc.org/golang.org/x/mobile

I didn't say you can't do it. I said, try to do it. The phrase "general purpose" must be stretched considerably in such a case.

Is there a language you _do_ consider "general purpose"?

Yes. More than one, actually.