Less that they don’t want other companies using it and more so they don’t want other other companies translating it into something they can use.
Basically, translating an instruction manual from German to Spanish.
No one is breaking any copyright laws or IP to do this. It’s the same how Steam created Proton to run Windows games on Linux. It’s translating code from one language to another that’s readable.
If Linux becomes the dominant gaming platform for gaming (not gonna happen, wish it would tho), there is no reason for a “Proton for Windows” could/should emerge.