God's crystal ball

In my personal encounters, freewill theists are so conditioned to the notion that Calvinism is deterministic while freewill theism is the antithesis of determinism that they're incredulous when I point out that freewill theism is deterministic too, just in a different way. 

Say the God of freewill theism gazes into his crystal ball. He seems the future. To be precise, he sees what will happen if he creates the hypothetical world, as shown in the crystal ball. 

Now, there's a philosophical argument that foreknowledge alone makes the future unalterable. I think that's correct. But that's not my argument here.

The point, rather, is that if God goes ahead and makes the world he sees in his crystal ball, then at that stage it's too late in the game for the future to be other that what he saw in his crystal ball. Once he creates the initial conditions which eventuate in that foreseen outcome, the outcome is fixed. 

To take a comparison, suppose I'm scheduled to drive a friend to the airport tomorrow. That night I have a dream. I dream that I drove my friend to the airport. Along the way, I see an accident at a landmark. I'm unable to find parking space on the first two floors of the garage. The first opening I find is on the third floor, C137, between a yellow Karmann Ghia and a red Alpha Romeo. As we approach the terminal, I see airport security speaking to an agitated man. As we walk through the concourse, I see a beautiful woman stride past me. 

I accompany my friend to the gate. After he boards the plane, I catch up on some email and text messages before leaving. I glance up and see the plane explode in midair, killing all aboard. 

Then I wake up. I pick up my friend at his house and commence our ride to the airport. But everything begins to repeat itself, just like the dream.

Suppose I have libertarian freewill. This story has two possible endings. On the one hand, I might choose to do nothing different than what I did in the dream. Although I find the resemblance to the dream spooky, I chalk it up to coincidence. It was just a dream. As a result, my friend dies in the conflagration.

On the other hand, when we arrive at the gate, after everything up to that point happened just like I saw in my dream, I tell my friend about my dream and warn him not to board the plane. He shrugs it off. So I tear his boarding pass into pieces, causing him to miss his flight. 

My friend is furious and yells at me. Airport security intervenes. At that moment the plane explodes just after takeoff. The security guards leave, having more urgent matter to attend to than our little fracas. My friend is dumbfounded. 

Now, up to a critical point, I could "change" the future. It could still go either way. If, however, my friend boards the plane and the plane takes off, then it's too late for me to change the outcome. I can't save him. He crossed a line of no return. My failure to intervene before that juncture renders the foreseen future unalterable thereafter.