As noted by Awful Announcing, Dockett tweeted out what can at best be called an offensively racist joke.
Apple has a new device out for Chinese people. The iOpener.— DARNELL DOCKETT (@ddockett) December 21, 2013
Unlike many people who make mistakes on Twitter, Dockett had no interest in apologizing, however. He even went so far as to point out that he won't apologize to someone who expected it.
It's one thing to be "sensitive," it's another thing to be inappropriate. Dockett's tweets are clearly a case of the latter.