Carbon fiber sear post seized in tube

The clamp is completely removed in the pictures.

The only movement I’ve been able to get is when it slid down about 1/2". So it’s not completely frozen, but I can’t pull it back out. I’ve tried twisting & pulling to no avail.

I’m worried about using lubricants with the carbon fiber.

The bike is new to me with an unknown history and the seat post is just too dang high to ride!