Spell Trigger...
(This is the case even for a character who can’t actually cast spells, such as a 3rd-level paladin.)[/I]
Full text is important here:
Spell Trigger: Spell trigger activation is similar to spell completion, but it’s eve
n simpler. No gestures or spell finishing is needed, just a special knowledge of spellcasting that an appropriate character would know, and a single word that must be spoken. Anyone with a spell on his or her spell list knows how to use a spell trigger item that stores that spell. (This is the case even for a character who can’t actually cast spells, such as a 3rd-level paladin.) The user must still determine what spell is stored in the item before she can activate it. Activating a spell trigger item is a standard action and does not provoke attacks of opportunity.
In order to have a spell list a character must be a spellcaster.
Is a wizard with a 9 Int still a spellcaster even though his book must be empty? {I know, this is a just an exercize to apply the logic of the rules as you have sourced them - no one would ever have a wizard with a 9 Int, IMO}. The character still has a spell list and can use a wand.