The Buller's note is correct. Rutherglen muscats and tokays are fortified wines in the style of a tawny port (not like vintage port). They are aged in barrel, and undergo oxidation before being blended in a solera type arrangement. There is a four tier classification depending on the average age of the blend, starting from the youngest - Rutherglen - then through Classic, Grand and finally the oldest, Rare.
As they are already oxidised when bottled, they do not improve with further ageing. That said, they are very robust fortifieds, and will not deteriorate to any great degree for years (assuming good cellaring conditions and a good cork)
The Bullers rare is a great example. I would serve it at the same temperature as a red table wine, at the end of a meal. It would match with any rich dessert (chocolate or caramel based), but is so rich it's often a dessert in itself.
Wine tastes better upside down.