No apology was issued. No "dig" was made. It was a correction of an imprecise comment that Thomas's thinking reflected that of white conservatives. Since at least 80% of conservatives are white, it was not actually wrong, just inaccurate, since Thomas's views likely reflect those of conservatives of all ethnicities.
Tempest in a teapot.
And I deem it likely that both liberals and conservatives, when reading multiple news articles, some over two thousand words in length, may glean the salient points in the first thousand words (or less) and then move on. Welcome to the Information Age, when those of us with jobs and obligations have to read selectively. If you're being honest, do you read the entirety of every long article posted here, or otherwise brought to your attention? (I didn't find the Clyburn piece all that interesting, tbh)