Sound reasoning when applied to the alien civilizations themselves. However, the dark forest problem (which is what the original commenter I think is talking about) extends beyond the idea that aliens may or may not have agressive traits, if you believe that there are thousands of alien races out there, you only need one to be technologically advanced and decide that humans are too "agressive" to be left alone.
Upate: Other people in the thread have mentioned 3 Body Problem, I would recommend taking a look, it completely changed how I think about this.
Upate: Other people in the thread have mentioned 3 Body Problem, I would recommend taking a look, it completely changed how I think about this.