I’ve heard you make this argument before, bhante, and I have long wished to bring it up with you, because I have to admit it doesn’t make sense to me. Whether the laws are descriptive or prescriptive seems to me to be beside the point. The point, I believe, is that there is no independent agent, and so choice is always determined by factors apart from the actual choosing. Free choice, even if only marginally free, requires an agent to stand apart from conditioned phenomena and that is exactly what Buddhism denies.
If I usually have toast for breakfast, but one day decide to have cornflakes instead, then there must be a condition for that change. The change cannot merely be the outcome of not being bound by descriptive laws; there must a be a reason why you make the new choice, such as a sudden positive memory connected with cornflakes. No change in choice can come about without such conditions.
So it seems to me that any choice is fully explainable in terms of the sum total of the conditioning that is working on it at the particular moment of choosing. There is nothing apart from those conditions. Because there is nothing apart from them, you cannot remove yourself and make an independent choice. This is so whether the laws of conditioning are descriptive or prescriptive. Even if the laws are merely prescriptive, you need something apart from the prescriptive conditions to take advantage of the fact that your choice is not predetermined. To me, freedom of choice is not compatible with Buddhism.
If you feel so inclined, I would be interested to hear your rebuttal of the above. 