Well there's a legalese loophole right there which doesn't forbid free redistribution of "Modified" Meshes as long as the original author is given his due credit. It only states that they can't be redistributed for free "as is". But then again, a good lawyer could pick that argument apart without breaking a sweat if the owner wanted to take issue with it and back up said issue with cash. The "included in" portion could be read to include modifications by an astute lawyer I believe.