Seems to me it was either unavoidable or Canadian air traffic control shouldn't have let them land in those conditions.
Nothing to do with Trump or the FAA, as much as people would like it to be.
Never let a crisis go to waste I guess?
Because the NTSB helps investigates. And the host country leads the investigation.
And yes it could be anything, but most likely it was the bad weather.
If you're going to speculate, go for the most likely one.