Does anyone actually employ a 250 hour CPL / MEIR to fly an IFR twin single pilot?
I wouldn't say never, but immensely unlikely.
...I have however employed several 600-700 hour instructors in recent years who have ended up flying single pilot IFR twins within 6 months. It's not a first job, nor should it be, but it is handy to have the qualifications when your employer needs to put someone in the seat.
What the GA charter industry will look like in 6 months time however, with the NT and TAS in lockdown and no foreign tourists, nobody can say for sure.