Wow these cops are bad, I typed this in supercruise and came back to see at least 20 cops and navy vessels, some in ships as large as Pythons and Anacondas, trying and failing to interdict me. They had formed a crude flowing orb around me trying to get into position, but I was not at full or zero throttle so the AI apparently didn't know what to do xD
They let you go, it was the only reason for the ease of your escape. They're tracking you!