I think you may find that GA wouldn't have an argument against CAS being established to provide a 'known environment'. Their beef would be the establishment of CAS that wouldn't/couldn't be efficiently managed thus hindering perfectly valid access (The scenario I'm considering here is a Class D CTR which is managed by a single controller who, due to the high level of IFR traffic, doesn't have the capacity to issue VFR clearances that in all other respects would be perfectly safe).