I had private talk with Delph during my match with Digi as well, to ask whether Digi's actions qualify as "external posession" which is banned from the tourney.
However, he did say Minion's was special case and added that should I've beaten Digi in the match, then absorbtion of exorcised souls into Soulsword would have been valid for me and I could have saved those for playoffs and use as I please.
So it's not like Digi's the only one to possibly benefit from souls gathering, it's just I (for example) abandoned that route due to getting one character I've needed for general scheme of things only in playoffs.
And I never made that debacle public (maybe it's just me, small fish over here and not one of the main social threads attractions- had half-drunk SNK\alterntate sex love\Ash Crimson sucking ass conversation there out of boredom recently, though). In fact, the worst way to gain himself an "invincible debator\duelist" role in tourneys\turn based forum RPG is by badgering judges\mods asking for ruling into your favour.