Of course, the Democrats won't condemn the robber being armed...
Why should they, when he'll keep right on voting Democrat???
The article didn't say anything about his political affiliation. Black voters tend to vote overwhelmingly Democrat, but roughly only half of black eligible voters show up to vote. Big difference.
He was a male, black, in his younger 20's, and likely uneducated. All of these characteristics are under-represented at the polls.
In 2018:
51.8% of males showed up to vote.
51.4% of black people showed up to vote.
35.6% of people ages 18-29 showed up to vote.
42.1% of people with a high school diploma showed up to vote.
These percentages are in isolation. If we were to combine them and look at the percentage of young, uneducated, black, male voters showing up to vote, it would be at most 35.6%, and likely significantly less.
Simply put, the probability of him being a Democrat is much less than the probability of him being apolitical. Unless there is any indication that he's involved in politics, then it's not reasonable to assume he participates in political elections.