Or maybe someone misclicked. Headline is sensationalist, he could simply create a new twitter account. I don't see how this affects him attending the conference. Don't they send out email newsletters as well anyway?
I'd guess not unless money was involved. Personally I'd just stop supporting them by going to the conferences and tell everyone why.
But it also might be their way of saying "also pls do not attend again, we do not want ya".
But in terms of feeling rejected for unknown reasons, I'd let it slide. The reactions you describe (twitter blocking, "we don't have time to answer" emails) are immature, so expecting more from them is naive.
Since they haven't said "please don't attend again", don't interpret it that way. Don't reward people for communicating this poorly. If you can buy a ticket in your name, and you want to go, go. :-)