I mean in relative terms ...
It never ceases to amaze me that demonstrating such a weapon on civilian targets somehow made it past the entire chain of command. One of those things that I just can't wrap my head around no matter how many times I come back to it.
They weren't exclusively civilian targets, they were considered "mixed" targets. Hirohito's home wasn't considered strategically-important enough and therefore didn't make the cut.
The sites in question were also specifically selected because they hadn't previously faced conventional attack, enabling a more accurate damage assessment.