I gave the Cravers a try recently. I am confused regarding my options for when I conquer a world:

Recently I was playing a game and was trying to conquer my Sophon neighbors. I'd siege a planet for a turn or two then blitz it with overwhelming manpower. When I conquered it I was given three options:

1. Occupy - I take over the system, pops will be mutinous. No cravers will be there by default. I don't really like this option
2. Pillage - I like this option better but the tooltip indicates that for anything other than a dictatorship, you will take an approval hit. Not really sure why that is the case for Cravers. They are a conquering autocracy, seems like this type of action should GIVE approval
3. Consume - I have no idea what this does. See below.

Can someone please explain consume to me? I'm guessing this is a unique Craver option. The tooltip indicates when you chose this option the pops and system improvements will decay away over 10 turns or so. What do I gain from this action? The name "Consume" indicates I should be gaining something at the expense of the Sophons. My reward for conquering their planet (I'd assume). But when I select "Consume" nothing happens. I am not apparently gaining anything though. I don't see where the benefit is quantified, if anywhere. The "Consume" tooltip also says that if you colonize it after consuming, the colony will be created immidately and you'll keep all the system improvements. I had a colonizer ship in system waiting and as soon as I consumed the planet I was not given an option to colonize it. 

Am I misunderstanding something here? I'm sure I am. I'd really appreciate any insight and explanation behind this "Consume" option.

Occupy is the one you should be choosing, just pop a few slaves into those feeding vats and the system will be fine, Craver pops will start growing there immediately. I wish I could help you with consume, but I never picked this option, since taking the system is almost always better. More worlds to deplete, higher bonus from the last tier of craver collection thingy, slaves you can immediately send to your other worlds, new systems are nice.