maybe not a red ‘X’ then... but some thing to differentiate?
An arrow pointing “that way to the civilian airport” maybe?
On an instrument approach, you essentially have that. But, this airplane had apparently been cleared for a visual approach.
It would have been difficult to see the ground clearly, as it was 5 minutes after sunset on the ground. It's possible the pilots were staring into the sun just above the horizon (remember, they are at a higher altitude).