The finish date in the project view will pull the latest planned finish date in the event there are unfinished activities. When all activities have been marked finished, the latest planned finish date in that activity will populate as the actual project finish date. So with that being said, if a PM hasn’t marked any activities, it will pull the planned finish date of the latest activity as the project finish date. If some of the activities are marked finished, it will still pull the planned finish date of the latest activity as the project finish date. Hopefully the screen shots help to clarify my point. Let me know if you have any questions.