Skyhooks which are currently vulnerable can be seen by any player using the world map Vulnerable Skyhooks filter or by using the Colony Resources page in the Agency and choosing to view theft vulnerable Skyhooks.
Skyhooks will immediately alert everyone within 2 jumps of a Skyhook if a "friendly theft" is activated, just like the notification which would happen if a regular raid was at the 5 minute mark.
So the defender will not only notified instantly when theft began, and they can easily find out where?
you know you can ingore a lot of notification and only show the important ones right?
btw, nullsec alliance all have intel channel, as long as one person is notice that, basiclly everyone knows