It's an ethical measure because I use it to measure whether something conforms to my ethical values. I take it to be axiomatic.

Likewise, it's a simple assessment for me to conduct. "Do I think this corporation enforces that their product or service be used in a certain specific way?" Unfortunately, I'm incapable of formalizing it any better than that. Yes, it's arbitrary, and not rational. I accept that. I don't advocate that anyone use this test, nor adopt my ethical positions; however, it is what I use, and I was primarily interested in sharing my perspective (which is both arbitrary and irrational).