Self-employed Mechanic Section 179

Looking at 2 different answers in the help section: Section 179 is for business owners only. But later, someone says they are Volvo mechanic and asks if their tools are deductable and is told yes. I'm assuming this is only if he is a self-employed mechanic? So he cannot not deduct the tools as a job-related expense if he just works at someone else's garage? Is that correct?