Surprised that Israel didn't just decide to go it alone and build their own infra given the multiple reservations they clearly had. They have a vibrant tech ecosystem so could presumably pull it off
Most SWEs are still 20-40-something men, which would be the same demographic being called to service (I realize women also serve in the IDF, but combat positions are generally reserved for men).
So it's possible that Israel can't rely on their own private tech industry being unaffected during high-engagement periods.
I think the government does have plenty of its own infra (and military tech sectors would be unaffected by calling in reserves), but given the size of the country (and also considering its Palestinian second-class citizens who make up 20% of the Israeli population may not be trusted to work on more sensitive portions of its infrastructure) they're probably not able to manage every part of the stack. Probably only China and the U.S. can do this.
Iran attacking US-East-1 would certainly be unusual.
More likely is it was "aid" from the US which usually comes with stipulations about what/where they can spend it - common with weapons/military kit, wouldn't be surprised if they did something similar with cloud services.
And any offsite that is "Israel's gov offsite" is an easy target even if in Cyprus or NYC.
Comingling with a bunch of bulk commercial hosts is very safe from a threat modeling perspective (in this case).