Would Kozol argue that black people today experience more discrimination than they did when they were enslaved?

In his book, Kozol wrote about life in the Bronx; his narrative predominantly centered on the plight of impoverished Black and Hispanic inhabitants in the borough. Through his interviews with many of the children of Mott Haven, Kozol was able to conceptualize for the reader the deep problems that afflicted the disenfranchised and forgotten poor of the city.
Kozol correctly linked the widespread and established neglect in the Bronx to race. In 1990s, most of the inhabitants in the Mott Haven section of the Bronx were Black or Hispanic. Remember that Kozol wrote his book in 1995; based on his writing, it is conceivable that his focus today would remain the same as it was in 1995. Through his interviews, Kozol demonstrated that the neglect of Black and Hispanic residents resulted from an entrenched but misplaced ideology about the poor, rather than a strictly discriminatory attitude towards Blacks or Hispanics. It is true that many of Mott Haven's residents in 1995 believed, as sixteen-year-old Maria did, that white people looked at impoverished Blacks and Hispanics as "obstacles to moving forward." However, the larger issue remained the firmly established belief that the poor were largely to be blamed for their own predicament. 
From Kozol's viewpoint, this is an inhumane assessment of the systemic problems faced by Black and Hispanic residents in Mott Haven. Kozol may well argue that Black people in the Bronx continue to experience widespread poverty, but he may not necessarily conflate that argument with the rationale that Black people today experience more discrimination than they did when they were enslaved.
This is not to ignore the issue of race discrimination in the form of hyper-segregation in Mott Haven, however. Rather, the larger issue remains the established belief that impoverished residents were largely to be blamed for their own suffering. Kozol clearly showed that many of the same residents of Mott Haven were well aware of the prevailing social sentiment about "welfare queens," and he documented their distress at such sweeping generalizations about their plight. More than anything, many were discouraged by their own sense of powerlessness. 

"When we talk about the people who are making these decisions, we keep saying 'they' and most of the time we think of 'they' as being white. We don't even know who 'they' might really be, yet we keep saying 'they.' This is because we have no power to decide these things. Something's always happening where the last and final vote was not the one we made. So we say 'they did this' and 'they' seems extremely powerful, but we do not know who 'they' are."

The above words were spoken by Isabel, who voices the frustration many of the residents at Mott Haven felt. White people fled Mott Haven because they feared living in an area rife with crime. Their actions led to what Kozol calls hyper-segregation. However, Kozol's narrative reveals that many Black residents were equally apprehensive about the crime, poverty, and degradation in their neighborhoods. For example, David recounts his fears about his neighborhood:

"Some of these men...would burn their own house with their mother in it if they didn't like something she said...I don't know why...but that's the way it is. I feel afraid of my own people, my own race, black people, students my own age. You step on someone's foot or look at somebody the wrong way--if he doesn't like your attitude, he might pull out a gun and kill you."

Kozol also revealed that residents and law enforcement nursed similar sentiments of distrust toward each other. A resident named Kimberly described her frustration about the unreliable policing in her neighborhood. Kozol felt that in his zeal to demonstrate fiscal prudence, Mayor Giuliani (at the time mayor of New York City) failed to take into account the perspectives and experiences of all Black residents. Mott Haven's poorest residents blamed him for cutting social services many of them depended on and for being tone deaf on matters of social importance. Yet others argued that the mayor's tough policies on crime were to be lauded for lowering crime in the city's poorest neighborhoods. 
Perhaps, rather than comparing the level of racial discrimination between different historical periods, Kozol may well argue against a uniform interpretation of social issues within the Bronx community today.