"The online editor of conservative publication Quadrant has said it would have been preferable"
"if there had been a shred of justice"
"justice"; - just behavior or treatment. "just" - based on or behaving according to what is morally right and fair
So he is saying it is not morally right or fair that a bunch of young kids get blown up instead of the cloistered public servant snowflakes living in a publicly funded la la land actively promoting the religen responsible for these and other deaths ect.
