They could be “on vacation” when you start your attack… but remember, you won’t be able to kill it in one sitting. After that anyone can figure out when you will be returning to finish the deed.
If you face absolutely no defenses, or a roaming blob of players, a bunch of Oracles will tear it appart. But sadly, I find the citadels drops outside of wormhole space not so rewarding, as you’ll only get the citadel wreck to salvage (I salvaged an Azbel wreck with a Catalyst, ~120 millions ISK worth of salvage) and the modules fitted on the citadel at the moment of the explosion, not the hangars of the players inside, because of asset safety, sadly.