Scouts are using themselves up to propell themselves.Basically a scout is a camera on a fuel stack circling - and they need energy to transmit, to function and to move. For that they consume there whole body over time, which is basically just chemical energy compressed into a shape. And once that reaction is started it can not be stopped. Your scout will move through his whole life- even if its just vibrating in place -and that life will be short, fast and eventfull.
As the whole body consists of volatiles- one small bump going wrong, even just a laser light strafe, will set it on fire, uncontrollably. It could be potentially used for assault, but on impact, it would just propell itself away again..