re-read the narration. he had to. this guy's a fixer for the Gotham freaks. if batman comes to his office, and a few days later he'shitting the freaks in their cozy new lairs, the rest are going to know the realtor's playing both sides. and gotham ain't kind to rats
but because bats "beat the info out of him" (note the damage looks nasty but is superficial enough that he can have a drink), they'll shrug, since that's the price of business as usual for white-collar guys like penguin, making the realtor "on the level".
its also why Riddler hasn't been really targetted since going straight. the feaks know that while h's 'legit', he's scamming the rich and thumbing his nose at batman. plus, a probable "arkham's agreement" to not take cases that lead o his old buddies