Well, with his rude response, the pilot just lost any moral high ground he had from the original tweeter's unfair post. It goes to show that two wrongs do not make a right. The pilot (and Air Canada) had an opportunity here to display a calm, collected and classy response and show that they can stand up under pressure from frustrated customers - a basic part of any customer service industry. They failed. I see nothing here to warrant the pilot telling the customer to "shut it" when he could have just as easily explained the red alert, showed that the customer was being a bit unfair and walked away the better person.

EDIT: After reading through the entire thread - if the passengers had been sitting on the tarmac for 20 minutes and not given any explanation, then I think I can somewhat understand their frustration. How difficult would it have been for the pilot to just give a quick heads up to the passengers that there is a red alert, or some other weather-related explanation? I've travelled enough to know that delays on the ground can happen and wouldn't complain over a 20-minute delay, but communication is always a good thing in the transportation industry.