I have never doubted Trudeau's meanness.  Just look at the way how he dug  his father's grave in the Quebec TV debate in 2015.  Another hint is deliberate pick of rookies into the cabinet in the name of youthfulness but in reality easy control.  
Another one is how he staged close rapport with the corrupt Wynne to win GTA support.

Adding to the fact that he admired Gerald Butts, likely the meanest of all.