Yes, both.
The tragic thing is that workers were killed, and the population of genuine workers in Saudi Arabia is comprised largely of foreigners, many of whom are, de facto, slaves. (Imports from poverty-stricken third world countries who have had their papers seized and are stranded and forced to work or just. . . die).
The deaths of any such would truly be a tragedy.
Were any “non-slave” foreign workers killed, that too would be a tragedy.
Were any faithful Muslims killed, that would be. . . a mixed bag. Yes, tragedy that such might have died before repenting of their devotion to a Satanic hate cult and embracing the free gift of salvation in Christ. But still. . . devotees of a Satanic hate cult going to their just reward. . . OK, so I’m ambivalent.
Irony? Not only did this event happen on the anniversary of 9-11-2001 but the crane and the company using it are owned by Osama bin Laden’s father.
So, yes, tragedy and irony.
But. A part of me does wish this had happened during the culminating celebrations of the hajj, when the only ones injured would have been the most faithful devotees of The Butcher of Medina’s Satanic hate cult.