A comment thought of as a joke is read as an offense.
I propose to observe the distance between intention and effect: explaining the former does not automatically erase the latter. In the hypothetical example, the writer recognizes the discomfort and rephrases the message without accusing the other of being too sensitive.
Online communication loses part of the shared context. A concrete repair may require fewer words than a long defense, especially if the public has amplified the misunderstanding.