Uh, there's nothing about the robots.txt block that would keep the file from being indexed, so I'm not sure what theory you're working with ... They will index those pages as URL only or they (Google for sure) will use titles and descriptions from external sources if they can to keep them from being URL only.
If yours are not being indexed it's probably because there aren't enough links to them for them to be indexed without knowing the content anyway, but it's got nothing to do with the robots.txt block, because those pages will be indexed as URL only ... Check out the Google forum if you haven't ... This is one of the biggest points of confusion ... If you have seen the Google forum, then, uh, you should know locations blocked in the robots.txt are easily (and often) indexed.