Thanks to the generous help of Michael Cronsten (who's hosting a
catalog of old floppies), I managed to get hold of an intact version of Police Quest 2 demo:
https://drive.google.com/open?id=0B5j-_ZMS8_UoWWVJUldRTzJJRmMThis version is already recognized by ScummVM (same md5's as the corrupt version) and working flawlessly.
For the unaware - the only version available so far on the internet had a corrupt
RESOURCE.001.
6 years ago I managed to construct a "fixed" demo using views extracted from the full game. However, one view (
VIEW.010, shown in the final scene) was unique to the demo, which made my fix incomplete. You can read about it in this old ScummVM
bug ticket.