Re:
Penetrative fluids won't help here anyway, as there is no path through the bond.
Extreme heat and cold may help though. I haven't had a seatpost, etc.. removal job in ages but, I use freeze spray, that a plumber would use to stop water pressure.
Anyway, I digress. The rotation direction is correct, you just need to go for it, when you get an eighth of a turn, then bang some penetrative spray in....repeat...