How about a bushing that is a close fit in the swing arm with a hole in the center the diameter of the bolt. Use it to guide a drill bit to drill out the bolt. A lot of lubrication, a lot of pressure and very slow drill speed. You could also use a series of bushings starting with a small pilot hole. When you get near the final size, try a left hand drill. Perhaps the heat from the drilling will have softened e thread lock enough for the left hand bit to spin the remains of the bolt out. Otherwise, drill until all that remains of the bolt is a coil of threads in the swing arm.
Remove the drill from the hole and clean out the remains often. I'd use motor oil if cutting fluid isn't easy to find. I'd leave the shock in place.
'Gonna get me a six pack...push people off the highway!'
"they live off the carrion of our mutual distrust and bribe us with symbols that equate hatred with manhood."
"I mean at the end of the day, I was addicted to Starting Fluid for Christ's sake!"
"Yeah, that guy sure is terrible at touching moms"