This is actually my understanding, and the correct interpretation I believe.
In my view, if you allow 5-of-a-kind, you have to allow other screwy hands, like:Ģ wilds + 963 spades = flush, AA963 (each wild used as ace of spades), which beats Two flushes, AK987, say, one natural and one that uses wilds, would split the pot.
Whether a card is 'natural' or 'wild' should have no impact on ranking.
