2. They are allowed to have proprietary implementations of this protocol (let alone the fact that they created and opened up this protocol, so you could say it's their protocol).
Are they doing anything to close down the actual protocol?
The VSCodium folks drank the MS kool-aid and only later realised that the remote extensions are blocked. Now it's pylance, which will be THE python LSP for VSCode. This creates a lock-in effect. People who would have easily moved to VSCodium (which is VSCode minus telemetry) would stay with VSCode. And who knows what bit they would lock down next.
This is against the spirit of open source. Emacs or Vim would never do it, all the little Unix tools would never do it.
At least be honest like 'Sublime Text' or the Jetbrains IDEs. They have excellent software without the gotchas. They are upfront about what you are gonna get. Kudos to them.
[1] https://www.jetbrains.com/idea
With VSCode, it's not obvious. Whenever it comes up in HN, we feel it's open source. When one goes to it's github, one feels it's MIT licensed. That's why there are at least 3 issues in the VSCodium github asking why remote extensions are not working. It's like the excerpt from the 'Halloween documents' I commented above.
I don't think this is equivalent. It's their prerogative to not offer everything for free and/or make everything Open Source.
If they start banning Open Source extensions that do the exact same thing as their stuff, now that would be EEE.
Or if they change stuff in the platform to intentionally break Open Source extensions that compete with their extensions, that would also be EEE.
So far, there's no indication of that. This is just speculation.