The 990 defaulted to Dolby Digital because the signal was coming in as Dolby Digital; however, if you use the "Dolby" button on the remote to cycle around to Dolby Digital+Pro Logic IIx Movie, it will remember that preference for that specific input.

I've been in the midst of a debate about Pro Logic II/IIx recently (not relating to an Outlaw product), and one of the other participants worked as a sound mixer for TV - he confirmed that many sports broadcasts are still broadcast in Dolby 2.0 (although they may contain some cues to aid in Pro Logic surround decoding). It's apparently becoming less common, but it still happens. You would get more 5.1 content from a Direct TV HD receiver (in part because stations like TNT and Discovery use 5.1 regularly), but you'll still see a lot of Dolby 2.0. That's actually why Dolby requires Pro Logic II/IIx to be available for Dolby bitstreams - it lets those Dolby 2.0 broadcasts (many of which contain cues for matrix surround decoding) be heard in surround.