Mueller effectively says 'I was never going to accuse POTUS of Criminal Conspiracy in this report' [View all]
See the details spelled out in KPete's post here:
https://www.democraticunderground.com/?com=view_post&forum=1002&pid=12023618
In a bout of somewhat circular reasoning, he explains why not, which basically amounts to this:
Because of the fact that a Sitting POTUS cannot be indicted, per DoJ Prosecutorial guidelines, while DoJ Fairness guidelines direct that persons who WON'T be indicted for a given crime should not be accused by DoJ of having committing that given crime ... there was NEVER actually ANY potential for the Mueller Report to claim outright ... that POTUS was involved in a criminal conspiracy with Russians.
It was logically impossible for him to do so, based on DoJ guidelines.
And if you accept Barr's further interpretation (which is BULLSHIT) that a person can essentially never 'obstruct justice' *unless* there's an underlying offense for which they ARE prosecuted, clearly it would be impossible for a POTUS to ever obstruct justice, either, since he's above the law to begin with in terms of being prosecuted.