I think it's not so much a case of "we won't include stuff from modders" as it is a case of "we won't include your stuff if it's not within specified parameters".
So, if a modded plane is within the acceptable polygon limits, has accurate FM/DM and the modeller wants to share it with TD, it's not impossible to see it appear in an official patch.
At least that's the way i understood things when TD first announced their intention to gather some of the best 3rd party contributors and fuse their work into official updates. I could be wrong of course, in which case by all means correct me
