Don't remember if this was attributed to Ballmer or Ellison but it went something like "if open source has something we need, we'll just take it". End of story. The license is irrelevant. I can tell you definitively that tools exist to make open source software unidentifiable, even by the original author. Your best defense against this type of thing is simply "don't worry about anybody stealing your ideas. If your ideas are any good you'll have to ram them down their throats".