That's pretty shaky ground too, even if you can overlook the foundation being closed source, Valve aren't really known for supporting their engines very well beyond their own internal needs. They're not trying to be Epic or Unity.

The most obvious aspect to that is that Source 2 doesn't support consoles. Valve don't need it, so they didn't implement it.

Originally people thought the Source 2 sdk, was going to be released with Half Life Alyx, but it never materialized.