I picked up a cheap KS Dropzone for winter, but just failed to install is as I couldn't get the bolt into the saddle clamp. In frustration I ended up removing the post, then screwing the bolt in by holding the oval clamping nut with some pliers, and eventually it went in.
I'm worried I've crossthreaded it, something I haven't done for many years, as it's both stiff and looks a bit wonky from particular angles. However, the threads on both the nut and bolt look absolutely fine. So I wonder if it's just very roughly made, given it's a budget seatpost head. I did do the first 2-3 turns by hand, and only after that did it get stiff (which was actually when the excessive loctite coating met the nut). That said, if it was just the loctite, I'd expect it to feel fine after inserting the bolt a couple of times, but it's still rough.
So, who would still ride it? I can't see a replacement nut online.

Try a clean bolt. Run a tap through if it's still a problem
You can possibly retap the clamping nut a size larger if you have damaged it
It will just be roughly made, no way you would cross thread a M8 or M10 bolt and it not be stuck and/or very obvious.
Thanks, both, I suspected it is just shoddy manufacturing. I will see if I have another large bolt laying around