Unless you can solve this problem in a way that is publicly verifiable you can not be called provably fair and will always have someone calling you a scammer. Not because you are a proven scammer (that would be too late) or because you are disthonest (which can not be proven) but because you could scam.
I think you are not correct in this judgement. Both you and I carry signatures of dice games that accept investment in the bankroll. We already know, that the operator of these games can easily play & win in his own game as the seed in DB is known to him. In this case, we always give the operator a benefit of doubt, though his actions are not publicly verifiable. Do we leave him -ve trust because he
could scam ? In this case, I think, Vod is getting too partial to CrazyPonzi.com just because of the word 'Ponzi'.