The Audio Adds Up for Me
While the former CAA official may have done a great job in his interview, I don't agree that the audio of the captain trying to break in doesn't add up. It adds up for me. The captain was trying to beat the door down because he didn't have an angle grinder, pry bar or other tool that might actually do the job.
It doesn't matter how secure you tell me a lightweight aluminum-framed door is, if the person on the other side has control of a plane and is flying me into the ground, I will use the best tools I can find to try to get through that door. If I have no tool better than my shoulder (or a beverage cart), that's what I'll use. Now, if the door looked like a bank vault door, I wouldn't bother, but they don't look like bank vaults.
What was the alternative? Trying to smash a medical oxygen cylinder through a window to depressurize the cabin? I don't think that would work either. Pounding on the door may have been the least bad option.