If that is the case, then why does quicken spell state that you can not apply it to spells with a casting time of more than a full-round action? Shouldn't it say you can not apply quicken spell to spells with a casting time of more than 1 action casting time? That would seem to be much clearer. Although, the rules don't always seem to be written in the most precise manner. Perhaps it is just a case of poor wording.
Perhaps it is just a case of poor wording.