Those pins are NFG when they get stuck. I still managed to pass inspection last year, and only noticed when I went to change the pads this year that I couldnt fit two new ones on. The rubber boot of the lower pin must have been damaged (probably by the rump roast****s at Subaru syracuse) and allowed the grease to get out and salt to get in.
I worked the thing for an hour with liquid wrench and tapping/hammering/torquing alternatively.
I ended up using a pipe wrench and about 15 minutes of a cheap propane torch. I think what gets it stuck is the rubber boot, so I are basically going to just be melting the rubber until you break the vacuum inside. My bolt came out with the force and sound of a gunshot, so be ready for that.
Nice work finding a bolt and boot kit for $20. I can only find kits for both sides, and I gotta go to the nice folks at my local dealership for them.
Good luck, this was major PIA.