Assuming it is done above board. Why didn't guys who wore brown suits that didn't get hired at DAL sue? Because they couldn't prove it. This is war. And of course a union that has a good working relationship with management might be able to "suggest" that those that went to a foreign owned carrier were directly contributing to unfair competition, and ultimately cabotage issues that will probably arise before you and I retire... therefore... since resumes never get seen... ooops, just didn't make the cut. too bad.