I appreciate your analysis, but I don't agree with that point. Here is exactly what Rosenstein is quoted as saying:
As many article point of, if Mueller picks up obstruction, it opens up a conflict can of worms. Why open it, if you don;t have to?
Because they're trying to handle everything under this one SC, who according to the media has impeccable credentials, despite his obvious conflicts of interest.
Plus, there are some serious outward clues that Mueller is not handling the obstruction investigation.
There is basically one clue, the memo from Rosenstein, however it is completely indeterminate in whether that applies to the reports of Mueller looking into obstruction. Some have even speculated, that it is related to some information that is still yet to be released, since is specifically mentions bogus leaks coming from foreign countries, which do not seem to apply to the article regarding Mueller's potential investigation into obstruction.
I don't think we know anything for sure, but I'm not willing to give Mueller or Rosenstein the benefit of the doubt, based on Mueller's obvious conflicts of interest, his appointment of a Clinton Foundation lawyer to his staff, etc.
I think you are biased to that conclusion, which is your right of course. I don't know who the "they" is, as you make that assertion, but don't need to know or understand.
It's fine that we disagree by the way. My goal isn't to persuade you to abandon your point of view, it is only to express and justify mine. You have done the same thing, and I thank you for that.