I consider it an explicit part of emergency burn's utility. Let's say a fleet is tailing you but not willing to engage, and follows you through a small nebula. As you're clear of it and they're just coming out of it, you emergency burn and head straight for them. With the 100% acceleration buff, you can reach them unless they immediately also burn and pick an ideal course.
Changing Emergency Burn from an acceleration buff when turning to a debuff would mean that you'd have to slow down and start up again at normal speed before you engage the burn - more than enough time for the fleets stalking you to back away. Emergency Burn offering functionality to rapidly close distance in an unexpected direction on the strategic layer is a feature.
