And from the Spell Compendium:
This is the part that prevents reading a scroll as a swift action.
Magic Items: Activating a spell completion item, activating a spell trigger item, or drinking a potion is a standard action even if the spell from which the scroll, potion, or item is made can be cast a swift action, In other words, it takes a standard action to drink a potion of quick march even though casting the spell itself requires only a swift action.
This is the part that prevents reading a scroll as a swift action.