It’s pay walled, but the text I can see gives no indication that the cia could read the text. Just that at least 11 messages were sent. Sounds like traffic analysis.
11 messages with a few hours before /after? makes sense, and let the Saudis think that we know the what the messages say. If he sent e message every 3 days normally and then sent 11 the day of the killing...
These are messages between MBS and the guy organizing the killing, not MBS messages generally which would be rather circumstantial.