So it's the rubber part that holds the bolt(?)
Like Marc says not much about it in manuals.
But in any case this should be a doable DIY job and probably doable w/o removing the swingarm - maybe try to heat it with heat gun (the part of swingarm will expand and rubber gets softer) and kick it out with bush first? In theory the (hard) rubber part should be glued into the swingarm hole (I may stand corrected). If so then it's the matter how much raw-force you need to get it out without damaging anything else (more straight-to-the-point method would be just to drill it out with correct diameter of drill). It might be a little bit easier doing it while the swingarm is taken off, but I guess not much if you know what you're doing - you have a relatively easy access to it when the exhaust is taken off.
Once it's off you must do some research puting a new one in - if you can get the correct part from BMW or not (if not I'm sure you can manufacture one yourself with a right diameter tube and a hard rubber part) and what glue to use to make it fixed again. No point on buying a new swingarm because of the worn bush part.
Just my 2c.
Take care, Margus