Normally I would agree. Things have been lining up for this theory. Why would Meuller indict 13 unknown people that he can’t possibly prosecute? IMHO he is not saving his own ass. He can’t get trump so he is opening the door for somone else(AG, Special Counsel #2) to charge everyone involved with russian links. No matter how small the left can’t complain. They are all over these 13 charges as the end of Trump.
Even though this can't be tied directly to Trump, the media is already claiming that this proves part one of the collusion- that Russian helped Trump.
And even if they get no farther, this is enough for the left to smear Trump.
In short, those 13 indictments were red meat for the left.
I think you are 100% right and it explains why the betting odds still show 35% chance of Trump not finishing his term. Americans know Mueller is not done, and he is bound and determined to royally screw with Trump.