See push event payload: https://docs.github.com/en/webhooks/webhook-events-and-payloads#push

commits:
An array of commit objects describing the pushed commits. ... The array includes a maximum of 20 commits.

I believe as per this StackOverflow answer that commit[0] is the oldest comment, therefore unless you have more than 20 commits this will always evaluate to false and the grading job will be skipped

I do not believe there is any reason to keep this condition so the simplest solution is to remove it