By putting the income on line 8z, it is treated as unearned income. So, his standard deduction is only $4831 (4431 + 400).
If you want the $5800 to count as earned income, you have to treat it as self employment (15.3% tax vs 10% saved with a bigger standard deduction). It's not wrong to treat it as a one time gig exception, but that's the consequence.
