Yeah, security might be the reason here. Does not explain the 11 AM curfew though, which would bother me even more than the 10 PM closure.
If it was 6.00 AM or sunrise till 11.00 PM, I'd say: Ok, not perfect, but managable.
But 11.00 AM till 10.00 PM, aka 11 out of 24 hours of the day? I'd...