Copyright worries, I believe. Wine is paranoid of contributors who may have looked too closely at Windows or reverse-engineered it in potentially risky ways. I am vague on details.
Also, Wine is LGPL and ReactOS is GPL, so no code can flow in that direction.
uaygsfdbzf, you are marked as dead. I believe this is due to a somewhat brusk comment you made earlier, but your other comments deserve to be seen.