You are correct. I am not aware of any IHUB rule against you posting a PR from MIKP unless you are paid by MIKP to do promotion.
Similarly, if Cornerstone isn't paid by MIKP, then there's no IHUB rule against him posting his opinion of MIKP here on the MIKP board while also hosting this "conference". Zero evidence has been provided that he has been paid. This was just another in a long string of unfounded and/or misguided allegations.
My guess, and it is only a guess, is that Cornerstone does these sorts of investor calls to build Cornerstone's brand, to increase the value of his investment in MIKP, and to provide Cornerstone's Discord members and others with access to high-quality information about MIKP.
I'm excited to hear what Mark has to say! I especially like it that Mark is excited enough about MIKP's direction that he's willing to do this meeting.