First this says fireworks is points be default, then says its pixels by default. then says you can change it, then says you can;t change it.
So far, in my CS5 fireworks Im seeing the type is points and NO way to change it. which really doesnt make a lot of sense to me. ALL web design wants fonts to be precise, this means POINTS, yet there is no way to change the fonts to pixels. If there is a plugin that can help with this someone help me because this has been causing so much frustration for me and my team that Im considering giving up fireworks and going back to photoshop and GIMP. ODDLY even though photoshop is not a web tool in the same way that fireworks is, you can have your type set to pixels.
Your confusion is completely justified.
If you look at the upper right-hand corner of that Help page, it says that the topic also appears in InDesign, InCopy, Illustrator. I believe that the instructions you're reading are for all those programs, and that's why the text seems to be so contradictory. In other words, you're looking for information about Fireworks, and it's giving you information about multiple Adobe applications, with Fireworks being the exception.
So it's saying that, in general, across these applications, points are the default unit for text size, but you can change that unit in Preferences. Then it's saying that Fireworks is completely different: it uses pixels as the default unit for text size, and you cannot change that unit in Preferences.
I can tell you, without hesitation, that Fireworks 8 uses pixels as the default unit for text size. The reason for this, I assume, is that FW is intended only for web or screen output, whereas the other applications are intended for both print and web. FYI: Once upon a time, when monitors were 72ppi, a pixel and a point were the exact same size. Nowadays, monitors are higher resolution (I think mine is 112ppi), which means pixels are effectively smaller than points.