From the article:
In Missouri, 56% of black men graduate from high school, where 81% of white men do (National Table Data). 27% of white Americans have poor credit records, where 48% of blacks do (Study: African-Americans More Likely to Have Bad Credit | BadCredit.org). The reasons for this are an entirely separate debate, but it boils down to there being substantially fewer black men than white men who are qualified to be police officers.
Of course it helps if you want to be police, and I’m quite sure that falls under the category of ‘acting white’.