They had no need to?
USA is a country in North America, they are the one who station soldiers in another continent for no reason and continue to work with groups in the region to ensure instability. They should expect to be attacked.
Here an example where USA and Iran worked together against ISIS
https://web.archive.org/web/20230204083535/https://theintercept.com/2019/11/18/iran-isis-iraq-kurds/
“The battle of Makhmour represented another important milestone in the war against ISIS: It was the place where two foreign military interventions began. One was directed by the U.S.-led international coalition, which provided air support and later, heavy weaponry. The other, in the form of ammunition, training, and intelligence support, came from Iran. Over the course of a few short days that August, coalition airstrikes hit ISIS positions in the parched desert hills near Makhmour, leveling the playing field between the heavily armed extremists and the Kurdish fighters.”
About 1.5 million people did the Hajj. 320 is approximately 0.023% which cannot be used to draw any conclusion.
Then for those who don’t know, many people go to the “Optional” Hajj unregistered, which means they don’t have an indoor place to stay on or use transportation options and have no direct access to food. There are also the one who are old, the one who take their kids with them, and the one who are sick.
Again the islamic ruling is you do the Hajj “if you can” this include if it is during extreme heat you can just stop or never go in the first place.