For the record, here is the response:
Thank you for sharing your feedback regarding your inflight experience.
It is important to us that you know passenger safety is always our highest priority, and we work to provide a safe environment for every aspect of your travel. We apologize for your experience in onboard your flight and appreciate you bringing it to our attention. We do have policies regarding the safety of our inflight cart, and I'm sorry that the wheels were not properly locked. We take great pride in working to deliver exceptional service and are eager to correct errors and address issues when they are called to our attention. Your comments have been shared with the Inflight Manager for review.
Thank you for being an MVP with us, and, as always, thank you for flying Alaska.
Not that it matters but there was clearly a misunderstanding. I did my best to make clear that it wasn't the rolling carts, but the containers stored up high that flew out.