That line of site access is beyond incompetence. Given your background you should know snipers train to 1000 yards. Less than 200 is a bit hard to swallow.
I agree it was huge failure not to have that roof top cover and most likely other spots too.
The reason is the big question.
The SS planning documents should/could explain why it was not covered. The agent in charge has a lot of enplaning to do.
Maybe further up then that,