Board Thread:General Discussion/@comment-31338621-20170223022025/@comment-25449165-20170325000518

173.206.67.225 wrote: not that you entierly wrong but woulden't heathcliff be playing as "An Incarnate of radius", since it's the final boss?

That's an interesting theory right there, and it could be true. Kayaba was already dead but his "soul" was still alive, when he was talking to Shigemura. Kayaba himself indirectly created Ordinal Scale and the Augma, thus it would make sense that he would have some control over the full-dive function and the Incarnate final boss.