The Space X/NASA launch was canceled just 17 minutes before the scheduled liftoff. Due to risky weather, the launch has now been delayed until Saturday.
According to the captain, if they had an extra 10 minutes, the conditions could have changed, but the window to launch only lasts about one second and it would've just been too risky.
I also found two interesting quotes from Bridenstine regarding the launch.
"We are going to launch American astronauts on American rockets from American soil."
"We're going to do it here in the midst of the coronavirus pandemic, and I'm going to tell you that this is a high-priority mission to the United States of America."
The only reason I'd consider it high priority, is if they're already planning to evacuate Earth (or America) in the worst case scenario.