Yes, race becomes a quick and convenient proxy to judge class and affluence which can easily be confused with racism when it isn't even though the bias appears to be against a race.
But...that is racism. Stereotyping someone because of their race/ethnicity is racism. If a cop sees a black or hispanic person and makes a default gut assumption that they're more dangerous, and/or treats them differently because of race based assumptions, it's racism, because they're stereotyping based on skin color. That's one of the big problems with police in America (regardless of the race of the officer in question).
People often conflate things like racism and sexism with assumptions that it's calling someone a "bad person" by doing so. This is not true at all, in fact, almost everyone probably has aspects of racial or sexual bias somewhere, it's almost unavoidable because of humans evolving to classify things by gut, based on what they see and experienced previously.
The problem, and what people try to fight, is when this happens in a way that widely negatively affects people. When you have an institution like the police , making snap gut decisions based on what someone looks like, it can unfairly screw over people, and results in skewed treatment among large groups of people. That is what needs to be fixed.
This individual case in Baltimore has nothing in it where there can be a clear "they did this because of him being black" issue though. Him being black led to the position in which he was in (given the history of Baltimore and why so many black people are the underclass there), which can segue into the larger narrative, but this is not something that I would place more on a horribly run and managed police department as opposed to racial lines.