philly_boy, that's actually the whole point. These people want a neutral language that no one speaks as their first so that no one has the 'mother tongue advantage'. As you've probably already realized this would inconvenience a lot of people and cost a lot the re-educate everyone in the new language.
I thought just occured to me and, while I haven't looked into this, I think Latin may be more ideal than most people think. Many are against Esperonto to become a lingua frana because it is biased towards speakers of romance languages. This thing is with Latin, learners whose first language is a romance language will have an advantage with vocabulary but speakers of slavik and germanic languages will have less trouble with the case system. This seems to overcome at least part of the biased lingua franca idea.
I, however, do not believe that imposing a lingua franca will work, although if it can be done I'm not against it. I find that, when examining history, a lingua franca will arise out of need and over time, not from the wishful efforts of a group of people.