Yes,you can offer lending but you can't ask for loans without a valid collateral.
I think the tricky part for him will be getting or securing the collateral. You'll likely have to use an escrow for that as others likely wont trust you. I don't think there's much point in lending any way. The tips or interest are tiny and if you don't take collateral you'll get scammed.
look at the bigger picture; most of these loans range in the 10% interest range for a week loan; thats a 520% apr. that rate is better than any investment you can find on wall street. sure the amounts loaned out here are small, but its a nice side source of small near-passive income.