Getting a student loan is generally up to the lender. They can more or less set the terms as they see fit, so that they get repaid.
They might ask you to be responsible despite his age. Normally student loans are to be repaid after the education is complete, but you have to look at the terms of the contract to be sure. Be aware that student loans are not dischargeable in bankruptcy, so if he (or you if you were to co-sign) got such a loan and couldn't pay it back, bankruptcy wouldn't be an option.
I suggest that you look around (online and elsewhere) to see what student loans are available for him. It might help to qualify for a loan if he were to obtain a part-time job so as to pay at least part of the costs of his education.
Another thought: you might talk to a military recruiter to see what help the army, navy, etc. might be able to give him.
Please be aware that I may not be licensed to practice law in your jurisdiction, and therefore am not giving you "legal advice". You understand that an attorney/client relationship is not to be established.