Hi, I would like to propose this new feature implemented in an new pull request:
https://github.com/geoserver/geoserver/pull/1347
Basically it allows make a Layer Group explicitly not queryable. Currently, a layer Group is queryable if it contains at least a queryable layer, and the user can not override it.
See issue:
https://osgeo-org.atlassian.net/browse/GEOS-7294
There are opinions?
Best regards
Alvaro