You are so full of bullshit that it is coming out the top of your head. If the cops sue Trump it is a civil lawsuit so the only parties involved would be Trump and his lawyers, the cops and their lawyers, and the court. The DOJ would have absolutely no part in the trial. That statement issued by the DOJ was just the opinion of a Trump hating lawyer inside the DOJ. The opinion means absolutely nothing legally. A court judge will make the determination as to whether or not the cops can sue President Trump, not anyone at the DOJ. Since the DOJ wants the cops to sue Trump, that tells me the DOJ knows it does not have the evidence to justify indicting Trump for the crime of inciting a riot.