Hello Shellee,
Thank you for your question.
9.1.1 defines displayed material as:
“material appears within the flow of regular text and is set off from the body of the text by blank lines,
change of margins, or emphasis.”
Your example appears to show the text messages preceded by a heading. For this reason, I do not think following the displayed material guidelines in Section 9 would be the best choice.
Since text messages are essentially dialogue, I would recommend following the Braille Format Guidelines Section 14. Specifically, 14.1, 14.5, & 14.9.1
Michael