1) You have to make a call on obstruction.
2) But you can't indict or accuse. It's unfair to a defendant who can't defend himself in trial (Vol II, p.2)
3) So there's only one permitted result: Exonerate.
(The key error is #2)
Mueller came up with #2 (don't accuse someone if you can't put them on trial immediately). And it's ridiculous.
“Now please read this 400-page cryptic dense report that almost accuses a president of a crime, but I make sure not to do so clearly so the public understands he committed crimes...”