In this case he's saying > since I cannot sort this out in person due to the COVID closures ...which I interpret as "the office I would go to to sort this out

In this case he's saying > since I cannot sort this out in person due to the COVID closures ...which I interpret as "the office I would go to to sort this out is empty; there is nobody there; the lights are off and the doors are locked. Everyone who would be working there is working from home."