I think your impression is correct. If I'm not mistaken, Atyy was joking.
String theorists definitely used to do quantum cosmology, and get their string quantum cosmo papers cited. I just did this search at Inspire and came up with 50 papers:
Keywords "quantum cosmology" and "string model".
There are a number of recent papers but (if they are research and not merely multitopic reviews) they seem to be cited seldom if at all. Could something have happened to the perceived quality/relevance of string QC research?
Inspire, being beta, can still act unpredictably. If you try the link and don't get 50 papers please let me know. I'm trying to assess how stable and consistent the search is at Inspire.
Yesterday I got 20 recent string QC, 2009-2011 (8 with "membrane model" and 12 with "string model") and today so far I can't duplicate that.