He arrived at Omega while on his Pilgrimage, but was trapped when all his money was stolen and he could no longer afford to leave. Another merchant, Harrot, is preventing him from earning enough money with his salvage operation to leave the station by forcing him to sell his goods at higher prices, costing Kenn business.
Shepard can persuade Kenn to lower his prices or offer to convince Harrot to release the quarian merchant from the agreement, thus allowing him to set his own prices.
If the Commander intimidates Harrot into nullifying his agreement with Kenn, Kenn shows his gratitude by discounting his wares if it wasn't sought out earlier. Kenn still needs to make a thousand credits to buy passage off Omega, which Shepard can also offer to pay out.
If Shepard convinces Harrot to buy out Kenn's shop, the quarian disappears from his kiosk but the discount Harrot gives Shepard to all his stores also applies to Kenn's former store.
If Shepard straightaway gives Kenn enough credits to buy a ticket off Omega without even haggling, however, Kenn leaves his kiosk without so much as a discount.