Looking at the Airport's website, the previous arrivals and departures boards have now been replaced with a notice which implies that the three remaining air routes, Heathrow (temporary replacement for Gatwick, and London City); Manchester; and Liverpool are being operated on behalf of the Manx Government "for patient transfers and key workers only". It also seems to say that you can only book on these flights if you first have written permission.
The only two airlines involved are BA, and Loganair and Loganair are operating for BA anyway. I assume that all three routes are being heavily if not completely underwritten by the Manx Government.
This situation very much brings to mind the WW2 system where the IOM-Liverpool route was one of the few remaining operated by civil registered aircraft (DH Rapide), but completely under military control. You could only get on the service if you had military authorisation.
At least the windows on the Loganair Embraer 145 aren't yet covered in black out paint!