I know we're going in circles here a bit, but let me give you an actual data point. Flew Thursday 15th HKG-NRT-US gateway on JL. HKG-NRT flight was delayed because of thunderstorms in Hong Kong, which meant we would miss the onward NRT connection. JAL held our onward flight for over an hour in order to accommodate our delayed (and other) planes. The FA explicitly mentioned that they were delaying the US outbounds that day in order to minimize misconnects as all of their long-haul flights for Friday 16th were already cancelled and they wanted to minimize passenger disruptions, as people would be stuck in NRT until Saturday 17th at the earliest.

Arriving at the US gateway, all the return flights to NRT and HND were cancelled. I could see them towing a number of JL planes out of the gates to hangars, instead of loading them with passengers that would be landing on the 16th.

My guess is that had this been a US airline, they could have cared less about leaving people like me stranded in NRT and then tell me that due to "weather" I was on my own. Ironically, the reason we were delayed out of Hong Kong is that we waited for a bit for some passengers coming in from PEK (I guess on another OW carrier). Had we abandoned those passengers, we could have made it out ahead of the thunderstorm that grounded us for about one hour in Hong Kong.