That wasn't my point at all. (I can't even figure out which part of my post you think I said that.) My point was that some people need to cancel all previous US Airways cards and then possibly wait a long time before they can churn it, while others can churn it while still having one or more US Airways cards open.

It's oversimplistic in my opinion to treat churnability as a simple "yes' or "no". The rules for churning for each bank/card/offer can be different (and sometimes complex and sometimes YMMV), and you have to understand the churning rules for a bank/card/offer, not just whether it can be churned or not.