I don't care how involved he is in the case, I read his writing and I found it to be illuminating -- far more so than anything else I'd read on the subject.
You can happily take the opposing view simply because he is involved and is probably biased, but that will make your viewpoint almost entirely baseless.
Mueller has a history of doing an excellent job working things that aren't actually reasonable to informed parties that seem illuminating to people that aren't informed. It's actually a fairly key skill for a professional propagandist. I haven't actually read the piece on question here, but appearing illuminating and actually being deceptive propaganda are not mutually exclusive traits.
if that's the case, it's the job of the 'informed' guys to write similarly illuminating counter-arguments, because I've not found any yet.
The illusion of illumination is greatly enhanced by having a strong guiding narrative, which is easy with propaganda, harder with reality.
You cannot cry propaganda without providing some evidence as to what is misleading or factually incorrect, because otherwise anyone can say anything is propaganda.