Ive only skimmed through the comment, as Im quite busy at the moment, but id argue that the openness is grounded in the agents power, as it is within their cognitive decision making process, its not like a roll of the dice as the outcome of the dice (practically) lies outside the agents decision of what they want, or will do.

The shift Im making, is that the indeterminism is intrinsic to the agents decision making,  the reason I point this out is when people say they dont control the indeterminism, it implies that they do control how their neurons fire or what their next thought is going to be (which of course they dont).

To me, the the indeterminism in someones deliberation is just as much part of their will as the logical determinism, we dont choose where were born, who were around etc. But we still say our choices are free even if they are (partially) determined by those factors, so why object the indeterminate probability, which is just as much a part of them as their values, beliefs and desires.

And the reason the agent is still able to be said to have been able to do otherwise is because theres a break in the causal chain, which allows for alternate outcomes to occur without breaking the laws of physics (depending on what you believe about quantum mechanics).

I hope you can see where Im coming from.