not that it means they'll be willing to use it.
Based on the best knowledge of sentient beings that we have, it is more reasonable to believe that they will have weapons and are willing to use them than not.
Modern warfare is mostly achieved through moving objects (bombs, missiles, bullets, sharp objects, eventually directed energy) from point A to point B (the target). An alien species capable of reaching Earth would necessarily be masters of moving matter from point A to B, most likely at extremely high speeds. If you can travel between galaxies, you can war.