Thanks for the quick note. I thought of this question halfway watching the video. Now, having finished the whole series, basically the answer would be on a case to case basis. It depends to our creativity and imagination. :D
You question is very interesting. I've checked the lesson and I think it is because you only want to change the status on onClose since it makes sense in the context of the process and not in the context of the screen itself.
You may want to use the screen (and not in the middle of the process) and click on the button and not want to change the status.
I think that's the main reason here.
In this example, the change of status is being done on onClose() of the activity. I am just wondering if this is the better way or just do it on the action when the button on the page is clicked.