"and said they were flying manually and that the computer had been knocked out,"
Much more familiar with the NG than A319, but is it likely that the 'severe' turbulence caused the AutoPilot to disconnect, requiring manual intervention from the PF?
If so, the Cap't could have easily come on the PA in a semi joking tone, saying something like "that was a big one, it even knocked off the autopilot". PAX translation equals "computer had been knocked out". While re-directing to Calgary, passengers have time to discuss what just happened.....and thus story twists alittle...."and said they were flying manually and that the computer had been knocked out,"
Just a thought....