A few months ago I resorted to the hacksaw method to get the seized swingarm pivot out of my brothers 1978 KTM 400.
The brother had tried to remove the swingarm about 10 years ago to start restoration of the bike, but when he could't get the swingarm pivot bolt out (seized in the bearing tube) he gave up and the bike went back to it normal position in the back of his shed.
The brother had been able to get the pivot bole to move a few mm by use of brute force / extreme violence before he gave up. This made enough room for me to get a hacksaw blade between the frame and the end of the swingarm pivot. Because KTM pivot bolts are made of some really good steel, it took 2 hacksaw blades to cut through each end of the pivot bolt. Once the swingarm was free from the frame, the tube nuts on the end of the swingarm pivot tube (they are a KTM thing) were easily undone and the pivot tube just slide out of the bearings. Luckily, all the required part are still available, so I didn't even try to get the pivot bolt out of the bearing tube..