I do not know of any requirement for 2 pilots for the B350 just because it is being operated in Charter category. I am happy to be corrected though.
There may be a requirement for a cabin attendant if the aircraft is carrying more than 15 passengers IAW CAO 20.16 Para 6
6 Cabin attendants
6.1 Subject to subsection 6A, aircraft engaged in charter or regular public
transport operations shall carry cabin attendants appropriate to their passenger
complement as follows:
(a) aircraft carrying more than 15 but not more than 36 passengers shall carry
a cabin attendant, except that aircraft:
(i) carrying not more than 22 passengers, at least 3 of whom are infants
or children; and
(ii) crewed by 2 pilots;
need not carry a cabin attendant if the duties and responsibilities of the
flight crew concerning the briefing and control of passengers in normal
and emergency operations are specified in the operations manual;
Most operators of aircraft capable of this number of passengers chose to use 2 pilots as CAO 20.18 mandated 2 crew if the aircraft was not fitted with an autopilot. Very few of these aircraft ( Metro 3/23, B1900, EMB 110 etc) have autopilots.
Jetcraft operated some of their Metro’s single pilot and also Jerry McGowan operated his B1900D’s single pilot on the night freight operation.
I doubt that the B350 would be capable of being configured for more than 15 passengers especially in a medical configuration.
I am specifically not commenting on any use of the B350 in RPT operations.