Yes, nothing points to the inventor of the format and maintainer for decades has done anything with the format to make it suspect. If so, the recent backdoor wouldn't be needed.
It's good to be skeptic, but don't drag people through the mud without anything to back it up.
Also, the exploit shows a high effort, and a high level of competence, and a very obvious willingness to play a long game. These are not circumstances for applying Hanlon's razor.
It's weird to have one set of standards to a maintainer since 2009 or so, and different standards for others. This witch hunt is just post-hoc smartassery.
And this is in part because I can not even tell for sure that he even exists. If I had met him a few times in a bar, I would be more inclined to believe he is not involved.
Uh, because it's a compression library?
https://git.tukaani.org/?p=xz.git;a=blob;f=README;h=ac812ff1...
See what I did there?