Under his logic, that someone else would even be allowed to claim that you wrote the program shooting Shia Muslims.
Please stop pretending you know what my "logic" is. You have repatedly resorted to insults, and now you try to put words into my mouth.
Exactly, that's absurd. And if it were true, the FDL would protect against it only WRT the invariant sections. I.e., someone else could still include libel in the non-invariant sections and pretend it was yours.
Include means the addition, not modification. If you out right add such material, yes. If you modify it in some way, say by replacing s/I love/I hate/, no. There is nothing absurd about this.