I was looking at that bolt, or more specifically the nut, the other day.
I was wondering what to do if it seized. It's a compete bastard though!
My best idea would be to try a reciprocating saw of some sort and try to split the nut with that, splitting the end of the bolt at the same time obviously.
Flames would seem like a bad idea, but I wonder if it would be possible to apply some kind of induction heat to the nut and bolt only?
My first thought about how to do that would involve a stick welder, but could get dodgy!
I've seen a spanner dissolved in seconds when it shorted across a lorry's 24V batteries, so there's a thought, but could get dangerous! The spanner mentioned branded the guy's hand before he could let go of it. (He deserved it to be honest!!)
I reckon a dab on each end of the bolt with 24V jump leads would scare the life out of it!..
My bolt was out less than a couple of years ago when the shock was serviced and I'm just hoping that I applied my routine moly grease to the threads.
Might have the swinging arm out soon, so that'll be a good time to replace the bolt and nut with Ti and Moly.
Good luck with the horrible thing mate, and don't hurt yourself!