In what sense might price supports and ceilings actually hurt those they are intended to help?

Although the long-term trend is towards zero rent controlled apartment, rent control presently covered about 38,000 apartment occupied generally by an older, lower income population who has been in occupancy since July 1,1971 or by their lawful successor.
As an employee of the Department of Housing Preservation and development (HPD) and the only one pursuing a graduate MPA degree, you have been asked to sit in on the control guidelines based on New York City Rent Guidelines board recommendation.
However, an economist testifies before the Council that rent control lowers the level of housing in the same manner that minimum wage lowers the level of employment. You report back to Council speaker Mellssa Mark- Viverito and Mayor Diblasio who cannot understand how price floor and ceilings can have the same effect on quantity.

1)Please explain this seeming inconsistency in the economists testimony including supply and demand ((graphs in your illustration)) I have the graphs dont do it.
2) When governments impose price in an attempt to help some particular group of producers or consumers, there are often unintended consequences. In what sense might price supports and ceilings actually hurt those they are intended to help?