Full time student doesn't matter.
The standard deduction for most people is $12,550 this year, meaning he doesn't owe income tax on amounts less than that. But as an independent contractor, he still owes self-employment tax.
Also, that $12,550 standard deduction is not universal. If a person under age 24 has unearned income (income not earned from working, like investments and prizes), their standard deduction may be less than $12,550. That's called the "kiddie tax" and would add a form 8615 to his tax return, if that was the case.
