A couple of things about the Mueller Report and the media blogs concerning it:
1. Collusion is not a crime. A conspiracy to do something illegal is a crime. A conspiracy is an agreement between two or more people to do something illegal. Persons may be just as guilty if they aid and abet the conspiracy. Mueller found there was no conspiracy between Trump/Trump Campaign and Russia to influence the election.
2. With respect to obstruction of justice the media has gotten a number of elements of the crime wrong. Here is what the Ninth Circuit Court of Appeals' model jury instructions says with respect to obstruction of justice:
8.131 OBSTRUCTION OF JUSTICE— OMNIBUS CLAUSE OF 18 U.S.C. § 1503 The defendant is charged in [Count _______ of] the indictment with obstruction of justice in violation of Section 1503 of Title 18 of the United States Code. In order for the defendant to be found guilty of that charge, the government must prove each of the following elements beyond a reasonable doubt: First, the defendant influenced, obstructed, or impeded, or tried to influence, obstruct, or impede the due administration of justice; and Second, the defendant acted corruptly, or by threats or force, or by any threatening communication, with the intent to obstruct justice.
[The government need not prove that the defendant’s sole or even primary intention was to obstruct justice so long as the government proves beyond a reasonable doubt that one of the defendant’s intentions was to obstruct justice. The defendant’s intention to obstruct justice must be substantial.]
As you can see, the fact that an underlying crime was not committed is not a defense. Also, a person can be convicted of obstruction by trying, without succeeding, to impede an investigation. Finally, a person can be convicted of obstruction if only one of their goals or intentions was to influence the investigation. Obstruction doesn't have to be their only intent.
Mueller left it to Congress to decide whether President Trump obstructed justice in connection with Mueller's investigation.
I have tried to present the applicable law. The relevant facts are, to me, still unclear.