Good morning Vincenzo,
TDA Rule #44: Re-Opening the Bet.
In no-limit and pot limit, an all-in wager of less than a full raise does not reopen betting for a player who has already acted and is not facing at least a full raise when the action returns to him. In limit, at least 50% of a full raise is required to re-open betting for players who have already acted. See Addendum.
Player C raise to 18,000 is clearly a full raise over the 5,000 bet made by Player A and called by Player B. Therefore, action has reopened to both A and B. Player A, who is facing a full raise of 13,000, went all-in for 18,300. Action proceeded to Player B, who is facing a full raise or 13,300 and has all options available to him. According to the TDA Rules, if Player B calls the 18,300 then Player C will not be facing a full raise. In that case, Player C can only call or fold. Player C had raised to 18,000 while facing a bet of 5,000, an additional 13,000 on top of the 5,000. To reopen the action to Player C he must face a full raise of 13,000 or more. Otherwise, action is closed and Player C can only call or fold. So, if Player B's bet is anything less that 31,000, action will not be reopened for Player C.
The player called the floor and asked for clarification on a rule. TDA Rule #2 says that players are expected to know and comply with the rules. Player B's request for additional information is merely an attempt to follow #2. Of course, Player C will tell you that #2 also says that players should follow one player per hand. But, Player B wasn't asking for advice from another player, nor was he asking for advice from the TD. He merely asked for clarification on a tournament rule before making his decision. Therefore, I think the TD and player acted appropriately.
Regards,
B~