Well, as far as I can tell, the Authors file was removed completely. In all of the files that I could find that are old enough for him to have contributed to, his copyright notice remains.
In his own branch, the first commit is October 2007 and the vast majority of commits after that are from Lincoln de Sousa. So I don't think anyone was doing anything untoward here. I'm not really familiar with the project, but it doesn't appear to me that he was ever the original author. If anything, it appears as though Lincoln de Sousa did most of the heavy lifting and he was a regular contributor. I could easily be wrong, but that's my impression.
Still, acknowledgement as being an original contributor in the README seems completely reasonable and the issue has 14 thumbs up.
The first commit on github is a 77k lines commit that appears to be a migration of the project from svn to git. So you're looking only at later commit history.
In his own branch, the first commit is October 2007 and the vast majority of commits after that are from Lincoln de Sousa. So I don't think anyone was doing anything untoward here. I'm not really familiar with the project, but it doesn't appear to me that he was ever the original author. If anything, it appears as though Lincoln de Sousa did most of the heavy lifting and he was a regular contributor. I could easily be wrong, but that's my impression.
Still, acknowledgement as being an original contributor in the README seems completely reasonable and the issue has 14 thumbs up.