The ATC order does not permit ATC to initiate vectoring of, or assignment of altitudes, to VFR aircraft operating in airspace where the separation of VFR aircraft is not required by ATC.
You stated that if a pilot chooses to be in communication with ATC the pilot is then actually required to follow ATC instructions. No such requirement exists.
ATC is required to initiate a search whenever there is an unexpected loss of radar contact and radio communications, IFR or VFR.
I've observed many aircraft change to 1200 codes as they left Class C airspace. I'd call them, there was rarely a response.