Yes, "work together" means you work for free for Microsoft. Nothing more. Because you sign your code over to them, they are free to CLOSE SOURCE future version

Yes, "work together" means you work for free for Microsoft. Nothing more. Because you sign your code over to them, they are free to CLOSE SOURCE future versions at ANY TIME. Sure, you could attempt to fork, but the platform is proprietary and can lock you out (very likely in this case for "user security"). They are the biggest company in the world (by market cap) and those deep pockets mean they can outspend you until you go under or fall too far behind. It wouldn't be the first time.