I turned a steel drift in the lathe so I could tap or pound them out. If they are seized too solid to move all you are doing is expanding the sleeve in the UFM if you pound it too much. Pressing it out is an option, but an unlikely one for you right now (as is the application of heat). I would just spray it with Croil, or the equivalent, regularly to see if it will loosen up by fall if you are not in a rush. When it comes out I would install the new one with some NeverSeize.
I do not think it was designed to turn. Others may know more than I, but as a sidecar enthusiast, I would note that there is a three spring set-up that replaced the damper with a spring. In this set-up, the three springs needed more clearance than was possible with the sleeves used for the damper. This utilizes a longer F28/1, which is really an F28/3. Also used are two F57/4 sleeves which hold the outboard springs out further. On the RFM you have a longer bolt, F28/4. Then there are two sleeves, FT272 to hold the outboard springs out further on the RFM. Finally, There was SP5AS, which was a spacer and a special spring box eye to fit over the spacer so that the center spring was more securely supported.
I do not know if these parts were ever produced, or produced in small quantities, but I think that the sleeves were a design feature that allowed the flexibility to fit these items.
David