AFAIK JAR-OPS permits single crew AOC on some single-pilot aircraft (sometimes with operating limits, eg. single crew IFR requires operating autopitlot, even if that's not a certification requirement on the aircraft) but requires 2 crew for all jet AOC work irrespective if the jet is single-pilot.
I think the FAA system is much the same, and that the FSDOs that approve 135 operators tend to require 2 crew for jets.
Whether EASA and the FAA permit single-pilot AOC work is a significant issue for the cost and utility of the Eclipse in air taxi work.