You're absolutely right, I don't have proof. I can only refer the thread where another member broke his upper trying to remove the barrel nut, but that was most likely attributed to not using the correct type of upper receiver vice block.
I agree, no one gets the benefit of the doubt, but just because he can't break the barrel nut loose does not mean he does have the proper tools or knowledge to do the job. Have you never come across a front sight post taper pin that you thought you'd never get out? Or a fastener that someone was a little over-zealous with locktite on? Shit happens.

