How would he know what it feels like to get mugged? I thought the Federation was a post- scarcity utopia where they didn't have money, much less wallets or criminals.
I can't believe that anyone would happily choose to volunteer as a waiter in Daddy Sisko's resteraunt, or as the guy in the background vacuuming Starfleet Academy in Wrath of Khan. There must be some kind of compensation for doing these things. And if there is, there is something worth stealing.
Plus, Trip and Malcolm were mugged on Risa in ENT: "Two Days and Two Nights". No one said anything about Earth.