The cops who did that never said, "It's Giuliani time." That was a lie made up by Sharpton and the victims lawyers. Giuliani helped to save thousands of black lives by helping to dramatically reduce the murder rate in NYC. His anti-crime policies saved countless black women from becoming victims of rape. Countless numbers of black people in NYC avoided becoming victims of many other crimes as a result of Giuliani's anti-crime initiatives.
I don't know whether they said it or whether your claim is just a whitewash of the Giuliani record. In either case, his "successes" for the black community don't change the fact that there were notable attacks and killings of innocent black men by the police under his watch. Maybe the destruction of some innocent people by police is considered a reasonable price to pay in New York City. I'm not interested in having that policy brought to my neighborhood. Furthermore, that trade isn't going to play well among blacks in most parts of the country. I suspect that any Democrat nominee will regain the black vote in a big way if Rudy Giuliani is the nominee.