https://www.irs.gov/forms-pubs/about-form-8995
If the internship paid him as a contractor, rather than an employee, then he may be eligible for this business deduction. If he actively managed rental real estate, he might also qualify, but then you probably wouldn't be filling out his taxes for him!
Did he get form 1099-NEC from the internship or have other small business/contracting income (like a photography business or a lawncare business, etc.)?
