"Resource busy", as opposed to "this tool is no longer supported", almost certainly is a bug, and I don't read the blog post as implying otherwise. But that do

"Resource busy", as opposed to "this tool is no longer supported", almost certainly is a bug, and I don't read the blog post as implying otherwise. But that doesn't mean it's not reckless of Apple to introduce a load-bearing component that wasn't necessary before and then not properly regression test it across OS updates.