There is no way to know as to what the caption refers. We do know that it isn’t about the testimony of Jenteal as she hadn’t testified at the time of the porting.
Just because a person is engaged in a trial doesn’t mean his entire family is engaged or even aware of what is going on at the trial. They may care less what their father does at work.
# dadkilledit on the instagram refers to Mr. West’s cross examination of the states witness Rachel Geantel.