he is like leech they just cant use it around him and we are not sure about if he can suppress his power
The Haitian's ability to block the powers of others does not happen automatically. He has to willingly "turn his power on" in order to use it. Otherwise, Nathan would have never been able to fly away from the Haitian and HRG. And Peter would not have been able to use telekinesis to stop the taser when they tried to shoot him.