If we're looking at the recent Covid-19 detections, they are in (for example) Seattle and Manhattan, so these particular urban areas are likely among the first to need quarantine, and they aren't predominantly black.

Only a very small fraction of the population live in truly rural areas, but they would also be affected by quarantine restrictions on long-distance travel, and have a large proportion of "true individualists" who might be motivated to intentionally sabotage (for example) such checkpoints as a matter of principle.

Also, suburbs would definitely need quarantine, although it's easier in literal gated communities.

However, I think that you may have a point regarding the sensitivity of the racial relationships. If some government actions start harmfully affecting predominantly groups of one race (and it will be different groups in different places), then given the historically strained relationships in USA, it's likely that some of these groups will perceive the government as their enemy and try to resist any measures even if they're actually helpful for the health of their community.