There is currently no rotate 180 degrees option under Format > Character… > Position tab and Rotation / scaling as you indicate. The best way around the shortcoming is to use a text box for the text on this page and rotate the entire text box 180 degrees via right click (on the frame) Position and Size… > Rotation tab and set the Angle to 180.00 degrees. Why do I have to rotate the box? I often then have to rescale the box and many other things so that it fits again all.
Confirmed under Ubuntu 10.04 running: - v3.3.0.4 OOO330m19 Build: 6 - v4.1.3.2 Build ID: 70feb7d99726f064edab4605a8ab840c50ec57a ...thus version set to 3.3.0 release. Importance set to low in keeping with the linked bug below. The indicated behaviour probably goes back to OOo. A text box is a type of frame that does not support styles. The Insert > Frame... menu allows insertion of a frame that does support styles i.e., the Format > Character... > Position tab > Rotation options are available in this situation. So this is a partial workaround. There is however, no 180deg rotation option, either in a frame or for unframed paragraph text. Bug 48804 is trying to add this additional radio button option and this bug may end up being resolved as unnecessary should the linked bug be implemented.