SBR needs to make this investigation as transparent as possible to the rest of the contestants. Why poster A is paid and allowed to keep winnings and why poster B or C are banned from collecting prizes? If poster A colluded with posters B and C to defraud the contest then when poster A collects the top prize he/she will share top prize with posters B and C.
IMHO you can't punish 2 of the players colluding and allowing 1 to collect if you have proof they all 3 colluded to defraud the contest.
If there was no break of the rules then SBR needs to explain why they punished posters B and C and not A.