Imagine the response if any other nation had used nukes.
Everyone would have said - no matter who - they would not have been justified.
That's not the issue. Are you aware of some of the things the Japanese military did during the 1930s and 40s?
Are you aware of some of the things the Germans did during the 1940s.
We didn't throw nukes to them.
Sorry it's never justified. Period.
This is only a matter of circumstance and timing, if Germany was still holding their positions on the Rhine and the Oder in Summer 1945, Berlin would have been hit with a small supernova.