An interesting option that comes to mind would be having pre-specified codes that contain client-side (pre-baked in) messages, something like '1 - Wildfire alert: ...; 2 - Heavy rain; 3- ...; 1023 - False alarm: please disregard ...', possibly with another severity parameter to modulate messages etc.. Then at least no one could simply hijack the system to send arbitrary messages (only one of pre-chosen alerts).
"Sorry men with guns, the most we can do is send one of those messages."
"Sorry men with guns, the most we can do is send one of those messages."