I don't understand your pessimism. If Apple finds and fixes a gap in Wine's coverage/compatibility, those changes will necessarily be open source. Quite simply, any work which Apple does that could be useful to the wine project will be open source.
Obviously it would be nice if MetalD3D was also released under a better license, but it's hardly as though this omission is a big loss to the wine project.
Apple did not upstream anything to Wine here. They just use CodeWeavers code for macOS support, plus their own changes, and released a 20k line diff to be compliant.
The license to their translation layer(which is closed source) is very restrictive and basically only allows use for evaluation purposes.
> The license to their translation layer(which is closed source) is very restrictive
The Windows EULA didn't allow people who built their own computer to buy the cheaper OEM version of Windows. They were supposed to pay full retail.
I would expect to see people care about this license agreement restriction just as much as they did when they built their own PC and installed the OEM version of Windows on it.
So what you're saying is that Apple didn't do anything useful for the Wine project and you're angry because after Apple did nothing, they failed to open source the nothing. Okay then. I don't follow you.
Obviously it would be nice if MetalD3D was also released under a better license, but it's hardly as though this omission is a big loss to the wine project.