One of my acquaintances used to be an ATC (air traffic controller) and has many pilot friends from back then. They all say the same thing whenever they talk about the most important thing in aviation:
Have the courage to not take off.
Kudos to that US Airways captain for refusing to takeoff and stay put until everyone got on the same page.
And the first officer too. It's a team effort and safety is the responsibility of all crew members (including the flight attendants to call out something, jumpseaters and even folks dead heading).
I recall in a CRM training they asked the class what would you do if the captain wanted to take off and you thought it was unsafe. Various answers and one person said "I'd hold my feet on the brakes to prevent moving" to which the trainer said yes - that's the right answer.
Have the courage to not take off.
Kudos to that US Airways captain for refusing to takeoff and stay put until everyone got on the same page.