You'd use the normal VP table + the Necron table.
"At the end of a game, including normal Victory points, count up the Necron losses using the following modifiers:"
What is the criteria?
- "Any capital ship that is destroyed and left as a drifting hulk counts as 300% destroyed."
Nothing else. It doesn't matter if you hold the field or not as it's not a requirement; hulking a Necron capital ship is worth 300% VP to the person that did it, resulting in 465 (Shroud), 1125 (Scythe), or 1500 (Tomb Ship) + upgrades x3.