neutral ships can and do result in a negative number of renown points equal to the ships "reward" points. Sinking a "friendly ship will result in 10x the negative number of the same "reward" ponits. So if a ship is worth 350 renown points if it was an enemy ship, sinking the neutral of it would result in a -350 points. All that happens is that if you sink nothing else to counter-act that negative "reward", then you end up with a "Poor" patrol rating. If you instead sink 10 other enemy ships and end up with 3500 points, for an aggregate 3150 renown, you might end up with a heroes welcome and some shiny brass... it's all about the points in the game.
