I think the focus may have been on the wrong building.
I totally agree with you anon about the black windows being suspicious…. That is a possibility.
Have a look at this pic I mocked up. The appartment block across the road from the one you are looking at, has the ONLY clean roof in Hong Kong (lived there), and look how many "ham radio" (what you called them), antenna's on the top of that roof… Looks like a lot of tech in that building……