Ok so if the wage is that a single person can't get food stamps:Let's put it this way...
Livable wage should be when a single person working at the grocery store full time won't need food stamps to buy her own groceries.
Her job should pay enough for her to eat instead of asking the tax payers to help via food stamps
http://www.fns.usda.gov/snap/eligibility
For 1 person that means they can't have an income over $1276 a month. which assuming a 4 week month and 40 hours a week (you said full time) goes to just under $8 an hour. So where did $15 come from?
I'm ok with a minimum wage of $8. However my state is already at $10. So no one that works a full time job here should qualify for food stamps unless they are trying to support a family on that minimum wage job.