I am not a regular DL flyer so will defer to the experts if I am wrong but I just looked on Delta’s website and it says (bolding mine):

Check-in Requirements for Domestic Travel
The recommended arrival time at the airport is 2 hours prior to departure when traveling within the United States. You must be checked in at least 30 minutes before your scheduled departure time. Additionally, you are required to be at the gate and ready to board at least 15 minutes before your scheduled departure time. Customers who fail to complete the check-in time limits by these deadlines will not be able to travel on desired flights and change fees may apply.
https://www.delta.com/content/www/en...uirements.html

Seems pretty clear cut to me or am I wrong? And for #1 , did he arrive before T-15 or after? For #3 , definitely late and the photo of T-11 actually works against him.