I wouldn't worry about anyone but Microsoft stealing Wine. In order to develop Wine you must be an expert C++ programmer. That requires an enormous amount of work and thieves are usually lazy.
A new teacher came to the master. "I have developed some new techniques that make teaching much better." "How can I prevent other teachers from stealing them?" "Your worry is needless", replied the master. "If your techniques are any good you will have to force others to use them." With that the master threw an eraser at him.
The same can be said about Wine and Microsoft.