I will say, 8 games is pretty crazy for 1 gamejam. Most devs would usually submit 1-2 games. Since the games were published within the gamejam period, do you have any proof that these games were made before the game before I disqualify them. I want to make sure I am being fair since the rules state games made within the gamejam period would be accepted.
I found his scratch profile where he uploaded the original games. https://scratch.mit.edu/users/CoderNinjaG4mes777/
Also if you read the desc of some of his games here on itch you can see the date of the last build