I keep having to correct myself on this- I always say "DoJ won't indict a sitting President", but actually that's not true. The DoJ policy still allows for sealed indictments (I know you already know this, btw). So it's more accurate to say the DoJ won't prosecute a sitting US President.
Not that it's a huge difference rhetorically, but it's becoming a personal pet peeve of mine that I keep saying the DoJ won't indict a sitting President.