I would appreciate if you refined your above argument. You switch without acknowledgement from "[unqualified] proof" to "sufficient proof". Also, I don't understand why being an atheist precludes the acknowledgement and negotiation of subjective experiences, nor do I understand why being an atheist necessitates the acceptance of metaphysical realism.
Of course subjective experiences exist.
But perhaps I misinterpreted your implied claim that "the offense is in the offense taken." If what you meant was that the subjective experience of feeling offended is in the subjective experience of feeling offended, then I would have had no argument (and no need for any argument) against such a trivial tautology.
I interpreted "the offense is in the offense taken" instead as meaning that the offensive act, an act for which the person performing it may be deserving of censure, is sufficiently demonstrated by another person's subjective experience of feeling offended. That is not the case in any rational tort system, formal or informal. (See: "Spectral Evidence," in the context of the Salem Witch Trials, for a less than rational counterexample with predictably tragic results.)
Offense as a tort is negotiable, but in the same terms that any other tort is negotiable: in terms of the action taken. If, for instance, I use a slur and a person takes offense, a reasonable person will agree that I have offended -- not because someone took offense, but because I used a slur. If instead I do something that is not a slur except by a small group's abstruse theory that I was unaware of, such as use the limerick verse form, and someone takes offense, then a reasonable person is under no onus to agree that I have offended, no matter how much the claimed victims weep and wail.
In discourse on the Atheism+ forums, this standard is reversed. "Intent is not magic," but feelings are. So the limerick writer's lack of intent to harm and lack of any possible knowledge that harm would be perceived counts for nothing, while the claimed subjective experience of revulsion at seeing the horrible verse and meter on the screen is sufficient to establish tort. When the writer does not agree, he is further accused of the greater tort of denying the overriding importance of those subjective experiences.
If that's the way they want to run their own community, then that's fine with me. ("For God's sake, leave them alone," I believe was my precise recommendation.)
But it does imply that, under those rules, they have no standing to dispute theism, which is often based on subjective experiences. If anyone claims personal subjective experience of the presence of God (which many do), then by those rules, claiming that there is no God is denying the overriding importance of those people's subjective experiences, which is not permitted.
A system that privileges subjective experiences over all other considerations is simply not compatible with atheism. It is, instead, a form of mysticism.
Respectfully,
Myriad