How serious is the controversy over rent-controlled apartments in New York City?

This serious:

Queens District Attorney Richard A. Brown announced today that a Queens landlord has been convicted of plotting a near-fatal knife assault of two brothers who had a rent-controlled apartment in his building. A jury found that the landlord hired the second-floor tenants of his Elmhurst, Queens three-story brownstone to attack the brothers who were third floor tenants in order to clear them out of their two-bedroom, rent-controlled apartment.

District Attorney Brown said, “The defendant has been found guilty of conspiring to arrange an attack on his tenants in order to get them out of their rent-controlled apartment so he could raise the rent by $1,400 a month. He agreed to pay $2,500 to the assailants and fortunately the victims survived the assault. "

Evidently he didn't do what many New York City landlords do in this situation: bring in a new immigrant/tenant, put him in an apartment below the rent controlled one, and give a rent discount if they boil cabbage and animal entrails all day near a building vent.