I
'm sure that is the reason. Although I'm not convinced that terrorist attacks are flagged up in advance. So perhaps calculated risk rather than anything.
Your correct about the terrorist attacks of course, but the primary purposes of those assets are generally for threats from states. Hence rely on intelligence to determine the operational status of such.
Terrorist attacks utilising aircraft are supposed to be nipped in the butt at the departure point, or sorted out in flight. Hence those facillities and their operating hours should not be of any use in most cases.