I might as well add the plot armor of Valerian having the soul of the dead alien inside him, so the rest of them will not oppose him once they meet and the story can conveniently move in his favor without having to kill any of those victimized fellows. For a plot point that was foreshadowed in the beginning of the movie, he dismissed its importance early on, and the aliens on the multi dimensional bazaar did not do something about it right away.

And then it's the plan of the human general to hide the truth of the battle. How exactly would he do that where there were thousands of soldiers fighting on both sides? How do you hide the destruction of a planet by erasing footage and killing a couple of staff members? There were way too many witnesses, enemy side included.