My son is a graduate fellow at a university. He was born before Jan. 1, 2004, and cannot be claimed as a dependent on someone else's 2021 tax return. He contributed to a Roth IRA in 2021. He received a 1098-T from the university and Box 8 (Checked if at least half-time student) is not checked. Box 9 (Checked if a graduate student) is checked. Is he eligible to take the credit for qualified retirement savings contributions (Form 8880)?