Number one, generally trusting anything that isn’t your own eyes is considered a bad idea when it comes to the supernatural, we have no idea what they are capable of disguising themselves from. Number two, I believe the staring is more a reminder that they’re being watched, and that if they leave, the guard will see, having that many eyes on them may piss them off, or desensitize them. Best to stick with what works, definitely when at risk of apocalypse.