You can't honestly say Mueller is required to prove a negative for Trump to be exonerated.
You don't know the definition of "exonerate." It's NOT a synonym for "innocent."
But, you go ahead and pretend it is.
He was ACCUSED of colluding with Russians to interfere with the 2016 election.
He was CLEARED of those accusations.
That's the very definition of EXONERATE.
Learn something for a change.
No one said Mueller had to prove a negative. Mueller is a smart man, he knows full well that if his statement was limited to "we found no evidence of collusion" that the next question would be whether the evidence proved him innocent and he would have to add that the evidence does not exonerate Trump. Mueller's statement was succinct and precise.
Exonerate means to be proven innocent. I think you should read the definition you post because it supports my position and disproves yours. Notice the part that says "free from guilt". The investigation didn't show Trump free from guilt, it just found no evidence of guilt.
But perhaps you should look to a legal dictionary since we are talking about a legal issue.
https://thelawdictionary.org/exonerate/"It is more that just freeing an accused person of the responsibility for a criminal or otherwise illegal or wrongful act. It is publicly stating that this accused should never have been accused in the first place."
Again, absence of evidence isn't evidence of absence, I don't know why that is hard for you to grasp. Well actually I do, its because you are so biased in favor of Trump that you look at the evidence with the intention of finding King Trump innocent instead of looking at it to find truth. It can't be good enough that Mueller said there is not enough evidence of any crime, you have to nitpick that he stated the fact that Trump wasn't exonerated. How dare anyone malign Trump!
Jesus could come down from heaven and investigate Trump himself and the Trump lemmings would find a way of claiming Jesus to be a democrat puppet.
PS - I know this may blow your mind but I am not of the belief that Trump colluded with Russia nor am I a closet liberal. I am neither a never-trumper nor am I a Turmp lemming. I won't torture the facts to get them to support Trump or go against him.