Are you using SCORM 1.2 or 2004? SCORM 1.2 only uses cmi.core.lesson_status, whereas SCORM 2004 uses cmi.success_status and cmi.completion_status.
To my knowledge, Captivate 5's SCORM 2004 code will set cmi.success_status to 'failed' as soon as it's launched, and will not change to 'passed' unless specific criteria are met (in your case, a 70% score on a quiz). cmi.completion_status will be set to 'incomplete' until the learner has completed the course, at which point it should be set to 'completed', regardless of the value of cmi.success_status. Therefore, you should be able to achieve what you described in your post. I don't think this is possible if publishing using SCORM 1.2.