The rule that you are compelled to bet/raise last to speak with the nuts on the river is wrong and illogical imho. It is based on the seemingly reasonable assumption that the only reason you would ever fail to bet/raise the nuts on the river is if you are colluding with or softplaying someone, and therefore that this should be disallowed. However, this seemingly reasonable assumption is actually flawed. There are situations in tournament poker in which it would be a clear strategic error for you to bet/raise with the nuts on the river.
You are on the bubble. As the big stack you have been bullying the table relentlessly and increasing your stack steadily without ever seeing a flop. The entire table is playing far too tight as they are all trying to sneak into the money, and you have been relentlessly exploiting this. In this situation you want the bubble to continue for as long as possible, and it is actually detrimental to your EV if someone gets knocked out. The reason for this is, of course, that you are likely to be able to increase your chip stack even further if the bubble lasts longer, giving you an even greater chance to win the tournament when the bubble does eventually burst.
You have the nuts on the river. You are hu in the pot against a super short stack. He bets 2/3 of his stack. If you raise he will very likely call and will bust out of the tourney. At that point the bubble will burst, and some of your edge will go down since now your opponents will have made the money and will start to play more optimally. Therefore, raising would be a -EV play. It is in your interest to keep the bubble going longer and this is the only way to do it. In fact, if the short stack had pushed all-in on the river you should probably fold your hand. The EV you would gain from the bubble lasting longer is likely greater than the EV you gain from hoovering up the last of the short stack's chips.
Now granted, this exact situation is not likely to come up in a pure form in practice. However, variations based on its underlying principle will definitely occur. Clearly a player who chooses not to bet the nuts on the river (or even to fold the nuts) in this sort of spot can be doing so purely for strategic reasons intended to increase his chances of winning the tournament. So the rule that this should not be allowed is wrong imho.
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