I believe it was stated doing development that this event gives at least a class 5 planet.
That's fine, but the point is that, when the player is required to make a decision, the text presented to the player should accurately describe what each option does. When the text says that you will get a class 5 planet, but in reality you will get a planet that is at least a class 5, I believe that you are not providing the player with accurate information they can use to make a decision.
My memory is a little foggy, but I believe I have always gotten a class 8 planet. When you said "at least" did you mean that the class of the planet would be random, but at least 5?
