@Pat353 The biggest concern with incommunicado guests is usually that you don't have a 24-hour service desk and need to know their arrival time to schedule their check-in.
Since these guests have blown their chance to have a customized check-in time, what you can do is follow up in Airbnb messenger with a shorter window of time in which you are still offering the opportunity. I tend to suggest the last 2 hours of your advertised check-in window.
If you use self-check-in, this is less of a concern.