Colin is an NFL caliber football player. He does not represent the average American or even the average African American. Using him to guage the life of an average African American and the marginalization Black people are exposed to is idiotic at best.
To see whether the problem of disproportionate violence by law enforcement on african americans, we look at stats and studies on the topic:
YLLs(Years of life lost) highlight that police violence disproportionately impacts young people, and the young people affected are disproportionately people of colour.
Mapping police violence
Police Killings of Unarmed Black Men Affect Mental Health of Black Community
And finally, a google scholar search shows thousands of studies regarding law enforcement and African Americans/Latinos. Most studies support and prove the hypothesis that African Americans are disproportionately killed by law enforcement even when unarmed and when controlled for crime done(if a crime is committed).
At this point, it is clear that Colin's concerns are justified and, if you truly love America, you would also protest peacefully like him for the lives of your innocent American brothers and sisters.