I think you will find that it really depends on the minimum crew required in the AFM. Quite a few B350's are flown single pilot.
Also maybe any contract requirements for multi crew. I doubt that there are any.
Lastly a serviceable autopilot IAW CAO 20.18. I suspect a new B350 will have this and a very reliable and capable one at that.
More than likely these aircraft will be operated single pilot except for training and check flights.
A MTOW above 5700 KG does not in itself create a requirement for 2 crew. The aircraft certification for the minimum crew numbers will be the starting point then you have to consider a number of other factors. (rules plastered over multiple CAO's CAR's Ops manuals etc).