I suppose there are different opinions out there.  I am in the camp that this is the student's own support.

Why do I say that?  If I look at §529(c)(2), this is what it says (emphasis added):

529(c)(2)Gift tax treatment of contributions.—

For purposes of chapters 12 and 13 -

529(c)(2)(A)In general.—

Any contribution to a qualified tuition program on behalf of any designated beneficiary -

529(c)(2)(A)(i) shall be treated as a completed gift to such beneficiary which is not a future interest in property, and

529(c)(2)(A)(ii) shall not be treated as a qualified transfer under section 2503(e).

If these contributions are a complete gift, it is no longer the contributors' money.

Some argue that since these accounts are usually owned by the contributor and the contributor is permitted to change the designated beneficiary for such accounts, ultimate disbursements from these accounts should constitute support.  To me, §529(c)(2) seals the fate.  I may have missed it but I don't think I've seen anyone putting forward the technical basis for the alternative position.