Nice save, seriously. What kind of lube did you end up using? I've heard mixed things about using penetrating oil versus regular grease for a stuck post. Did you heat the seat tube at all, or just let it sit cold? Always looking for more tricks to try before going nuclear with the cutting.
I used a mix of half penetrating oil and half regular bike grease, let it sit for two days cold. The real trick was using a long breaker bar on the wrench, not some dinky little tool. Honestly I was just happy it came out without needing a torch.
I always believed grease was the answer, but penetrating oil actually worked much better on my aluminum frame. Just let it sit overnight without any heat applied.
Honestly, I've always had better luck with grease on aluminum. Penetrating oil can sometimes make things worse because it doesn't stick around as long. Grease stays put and keeps things moving over time, which is key for stuck posts. Like @nelson.seth mentioned, heat can help, but I'd warm the tube just a bit first before adding grease. Letting oil sit cold might not really break up the corrosion deep down. So for me, grease with a little heat works better, even if it takes more patience.