That's like saying that they were unable to find clear evidence that Trump did not commit murder. if Mueller found clear evidence that Trump didn’t commit murder, he would’ve cleared him of it.
“And the report crucially noted that if Mueller found clear evidence that Trump didn’t obstruct justice, he would’ve cleared him of it.”
I know, that is so bogus. You can’t prove a negative - that is why the burden of proof is on the prosecutor.
A prosecutor does not clear someone of allegations, they either prosecute or not.