I think the Nagasaki thing was the first time they realized

Couple of counterpoints with no agenda.

If that were true, then they would have stopped the Hiroshima attack. On top of that, the Bikini testrun was also a full fledged atomic bomb and should have alerted the aliens as well.

There has been numerous documented UFO entities that supposedly approached fighter pilots during WW2, much before the Nagasaki bombing, some of them even deactivating conventional weapons. Point being, they were interested in us even before the Nagasaki.

So we have to either deduce that these entities don't care whether we detonate atomic bombs or not OR that they do care, but we never actually detonated these bombs OR they somehow missed all the atomic tests and the two actual bombs.

I've never heard of conspiracy theories that they were not atomic though, whats that about?

https://decodingsymbols.wordpress.com/2021/01/22/74/