What would have happened if Mueller had decided to ignore the OLC opinions

that a sitting president can't be indicted because to do so would violate the constitutional principle of separation of powers? What if Mueller had decided, "Fuck that guy and fuck the OLC memos, he obstructed justice and I'm gonna indict his ass." Of course, the opinion stated in the OLC memos is not settled law, although the argument and the research and reasoning behind it is rational and credible, not "stupid" or "bullshit," as some have described it. Others, notably Lawrence Tribe, have made very good arguments to the contrary, as here: https://www.lawfareblog.com/yes-constitution-allows-indictment-president

So what if Mueller had decided scholars like Tribe were right and the OLC was wrong? Let's say he takes the evidence to a grand jury, which returns a bill of indictment actually charging the president and not just calling him an unindicted co-conspirator, as a Watergate grand jury did with Nixon. What would have happened to that indictment?

Most likely, Bill Barr is what would have happened.

The indictment would have never seen the light of day and Mueller would have been fired is what would have happened. It would be another Saturday Night Massacre but with no heroes like Richardson and Ruckelshaus.

Or, taking it another direction, let's say Barr didn't quash the indictment or fire Mueller but instead challenged the indictment on the basis of the OLC opinions. Now we have two parts of the same agency, the DoJ, fighting with each other in court - the Special Counsel vs. his boss, the Attorney General. How does that play out? And if it ever did get to the Supreme Court, how is a majority of this Court going to rule? Kroner to krugerrands they'll go with the OLC opinions.

So we're back where we started and Trump has run out the clock.