If a known liar and drug addict tells you that he have this theory, and proceed to make rational arguments for it, ignoring him just because of his reputation isn't very scientific.
It's ad hominem if dhechols' point was that a scientist's work should be ignored if he/she also holds religious beliefs. That's not how I read it. I see no fallacy in simply pointing out a disparity between scientific reasoning and (unscientific) beliefs.