He's aware there could be some ramifications to just up and talking to someone from out of the blue beside them, but he's kept enough distance between himself and the other man to give him reaction time if needed. Without any attempt, however, Dabi's left watching the smaller figure vanish into the crowd to go seek out another patsy.

"Guess that'll be a lesson to improve." Getting caught and managing to escape is simply an indicator you need to get better at stealing or dodging. He leaves the thief's departure and heads forward towards another stall. "Ya don't strike me as the kind to go peddling mushrooms around the night market..."

Meaning this man probably doesn't have another recourse. Offering barter suggests he's not willing to do blood (or doesn't know yet) or steal what he wants or needs. "Just get here?"